As does Sol Ring, Mana Vault, Mana Crypt, and Exploration. Basic mana dorks are just outclassed by nearly everything.

And Ancient Tomb as well, forgot that.

In almost every other deck I would agree, yet the dorks provide green mana rather than colorless which is what I think the reason for including them over artifact mana is.

Running 3 cards to specifically get Omnath out turn 2 just wastes space, and when you can use better alternative cards it just doesn't make sense to run them. For producing green mana there's much better ways such as Caged Sun and much better mana dorks than basic elves. If speed is an issue than the previous mentioned cards are much better. A late game to mid game mana dork doesn't do anything, especially when everyone plays boardwipes.

Wow, that's a lot of suggestions, thanks Quail! And thanks to Didgeridooda and NateJH for getting a discusion going!

Before going over the recommendations, it's important to note that I want this deck to be a creature toolbox deck. Which means that I want to handle most of my opponent's threats with creatures, even if it makes the deck a little weaker (it wins often enough in my meta as it is...). At this point, the only exceptions are Predator, Flagship, because it eats tons of mana, which Omnath can provide, and Beast Within, because it can hit any permanent, at instant speed.

The mana dorks provide for a second-turn Omnath, which is kinda brutal. So do Sol Ring and other mana artifacts. But the dorks produce green mana, which is right up Omnath's alley. And, most importantly, the're creatures. The aren't dead cards if I draw them later in the game. I can still sac them to Birthing Pod, or cast them to return another creature with Cloudstone Curio, or discard them to Fauna Shaman. I couldn't do these things with artifacts. All the other dorks you suggested cost 2 mana and don't enable a second-turn Omnath. And considering the Hexproof of Sylvan Caryatid: Anthing they do to my mana dorks, they don't do to Omnath, which is good in my book.

I ran Sakura-Tribe Elder for a time. I know that it's great creature and I run it successfully in other decks. But in here, Yavimaya Dryad is better, because it has an etb effect and I can cast it again and again. Once the Elder is in my graveyard, it's too much work to get it back.

Yes, Nissa's Pilgrimage has to be replaced. I tested it for its Spell Mastery, but it never worked... I'll probably test Verdant Confluence.

Animist's Awakening seems like a bad Boundless Realms to me...

Bane of Progress: It really is devastating. But it devastates me, too. I run too many artifact and enchantments to run it.

Song of the Dryads and Krosan Grip: As you said, they're not creatures. Great cards, but not tutorable when I need them.

Evolutionary Leap: It's on the shortlist to be tested. I run it in my other (partially) green decks and it does a lot of work, there.

Ulamog, the Ceaseless Hunger really should be in here, as he has a great etb ability. I'll have to see if I can get my hands on one. Artisan of Kozilek has a good etb effect, but Eternal Witness, Genesis and Praetor's Counsel have to be enough graveyard recursion. I run too few colorless creaures for Eye of Ugin.

Avenger of Zendikar: It doesn't deal with opposing threats. Yes, I could block some big creatures with the tokens, but Hornet Queen is far better at that job and works well with Craterhoof Behemoth, too.

All Is Dust (and Oblivion Stone and Nevinyrral's Disk): I don't really need them. There were some games when I wished I ran them, but even then I couldn't really tutor for them. I can tutor Ulvenwald Tracker, Duplicant, Polukranos, World Eater, Steel Hellkite, Cloudthresher, Stingerfling Spider and Silklash Spider. These creatures allow me to handle my opponent's dangerous creatures.

On the other hand, The Great Aurora seems like a great mass removal for this deck. I wanted to make a deck around it, but it never occured to me to use it in here...

Surrak, the Hunt Caller: It isn't neccessary for my creatures to attack right away.

Elvish Visionary and Wall of Blossoms: While I can trigger them multiple times, they're mostly filler 2-CMC etb creatures. They can go.

Acidic Slime: It is costly, yes. But it hits lands and is a great blocker. I'm never disappointed to draw it.

Verdant Confluence over Nissa's Pilgrimage, Ulamog, the Ceaseless Hunger and The Great Aurora over Elvish Visionary and Wall of Blossoms, and Evolutionary Leap, probably over Conjurer's Closet.

Thanks for your suggestions!

hyperlocke Have you checked out any Yisan lists? I made him for a really budget mono green since Omnath went a little too hard. Now the budget deck is almost as strong. Talk about toolbox commander. I know Omnath is better, but I find yisan really fun.

@Didgeridooda: Yeah, I looked at Yisan, the Wanderer Bard. Though mostly as a part of the 99. My problem with him is that he is sooo slow... But his lists have a much nicer mana curve than this.

Did someone say suggestions? Here's some more...

Worldspine Wurm (should be able to get him out with Omnath around - high game impact)
Drumhunter (very good Omnath card. his mana doesn't stay but his first ability is well worth it)
Patron of the Orochi (late-stage power boost)
Elvish Harbinger (you have enough Elves to justify it, and it can combo into cards like Yeva, Nature's Herald or Fauna Shaman or Reclamation Sage)
Gaea's Touch (interesting bit of utility; up to you)
Rofellos, Llanowar Emissary (your playgroup may hate you, but Rofellos is technically legal in commander as long as he isn't your general. more information here.) Nevermind, he got fully banned.
Somberwald Sage (because it's green mana, Omnath will store it, but it will still have the same condition. that being said, nearly endless supply of colored creature mana is REALLY nice.)
Freyalise, Llanowar's Fury (card draw + ramp + draws attention away from Omnath)
Lifeblood Hydra (massive card draw with a nice life boost)
Vigor (a relatively good protection for your monogreens - surprised you didn't include it)

Personally, I like running Tree of Redemption just in case. It's imo though, you don't have to include it.

In my own deck, which is here, I built it around a mechanic of elves and Helix Pinnacle + Primal Surge as a win con. There are no non-permanents in the deck, so Primal Surge mills me completely. Now that I have every card on the battlefield, I can easily win with Helix Pinnacle. Elixir of Immortality is a just-in-case card.

Oh...right, should have read the deck philosophy first. Usually there's not any additional information there that I can't already glean from looking at the deck. So scratch that Worldspine Wurm. Don't forget Candelabra of Tawnos, though.

One last thing that I totally forgot: Wild Pair. Yo, this card is hilarious. It makes basically every creature a tutor. It changes the board state so fast, your opponent's head will spin.
Here's what it would do for your deck:

1/1s: Fierce Empath, Wood Elves, Ulvenwald Tracker. You can also pick these guys up with any of the tiny 1/1 elvish mana rocks.
2/1s: Eternal Witness, Reclamation Sage, Yavimaya Dryad. Doing Eternal Witness and Reclamation Sage on the same turn would be sick.
2/2s (this is where it gets fun): Hornet Queen, Acidic Slime, Fauna Shaman, Solemn Simulacrum, Scavenging Ooze. Pretty much any combo of those is good, and some of those are just insane.
2/4s: Seedborn Muse, Duplicant.
4/3s: Temur Sabertooth, Kamahl, Fist of Krosa.
4/4s: Yeva, Nature's Herald, Genesis.5/5s (this alone makes the card worth it): Regal Force, Polukranos, World Eater, Craterhoof Behemoth, Steel Hellkite. Pretty much any of those combos strongly slant the game your way.

There are only 6/33 of your cards that don't combo, and most of those are your spider blockers, or insanely large things (like the 9/9).

You can probably guess why Wild Pair is one of my favorite cards.

Not to mention this rule, either: (they don't have to match power/toughness, just the sum)

"If you cast a 2/2 Grizzly Bears, for example, you may then search for any creature with total power and toughness 4. It can be 0/4, 1/3, 2/2, or 3/1."

So in other words, only 5/33 cards are nonbos with Wild Pair.
Stingerfling Spider combos with the 4/3s.

@InDirectX: Oops, forgot to answer you...

Drumhunter: He might work in here, but in contrast to what I already run, he seems too weak.

Patron of the Orochi: Seedborn Muse already does that for only my permanents and for less mana. Granted, the Patron could do it multiple times, but once is enough.

Elvish Harbinger: I run enough tutors. A tutor that just searches for a specific creature type won't make the cut.

Gaea's Touch: If I'd run such an effect, it would be Exploration, so that I can cast Omnath, Locus of Mana turn two. The problem I have with these is that they're completely dead cards in mid and late game.

Rofellos, Llanowar Emissary: I ran him until he got banned. He was ridiculous.

Somberwald Sage: Yeah, her boost would be great. I don't run her for simplicity's sake. Keeping track of two kinds of mana would get too confusing in some games.

Freyalise, Llanowar's Fury: You're right, she has three very relevant abilities. I run her in another deck with great success, let's see how she does in here.

Lifeblood Hydra: Hmmm. seems nice, but I'm not too sure. Gonna test it.

Vigor: I really don't care too much about my toolbox creatures dying. They have done their job when they entered the battlefield. Also, I can get them back with Genesis and Mimic Vat.

Tree of Redemption: I think it does too little in here.

Candelabra of Tawnos: Seriously? I mean, this isn't a budget deck, but this card alone is worth just a little less than the whole deck. And it would only work with Nykthos, Shrine to Nyx...

Wild Pair: You certainly made a strong point for it. I don't really know how to feel about this card... I will test it.

Thanks for your suggestions!

Exploration continues to be insane mid-late game when you have a Courser of Kruphix on the field.

Invaluable cards to have in a mono-green deck, especially now with Woodland Bellower.

sick deck, i have my own Omnath deck, though i took a very different approach... Om Nom Nath

I am going to have to think about a few of the cards you have in your list... i am especially a fan of Wild Pair and am going to see if i can get it to work in my list.

Well done

have you considered Blade of Selves? all copies will trigger etb effects.

@Gabtuls: Thanks! Yeah, Wild Pair is tons of fun (for me). Even if I don't really need any toolbox creatures, plastering my board with creatures and then searching for Craterhoof Behemoth is always good.

You run lots of high P/T creatures, so you probably won't find as many matching pairs, so watch out for that when you decide to test it.

@mikaellee I did consider it. Right now, I honestly can't say why I don't run it. It might have been to inefficient, or it might have been the price tag at the time it came out... I'm gonna test it again, thanks for the suggestion.