This is a build based around Yeva, Nature's Herald as the commander that comes in under $25 to keep things on budget. It doesn't run any individually expensive cards except for Seedborne Muse since that card is very good when all of your creature's have flash due to Yeva, Nature's Herald. The game plan of this deck is to use Yeva, Nature's Herald to play our valuable green creatures at instant speed to make them more resilient to removal and more dangerous for our opponents to play around.
Since this is mono green the mana-base is simple. Out of 40 lands, 37 are basic forests. The other 3 are inexpensive with useful effects where Mosswort Bridge allows us to hideaway a card and the other 2 lands simply tap for a green and can cycle if we need to. Rather than running mana dorks that mainly stay on the board, this deck wants to run creatures with ramp effects when they enter the battlefield.
We run some tutor effects to help us find which creatures we need in specific situations but mostly our plan is to play valuable creatures at instant speed and win through combat damage against our opponents. We can recur creatures from the graveyard fairly easily with a variety of cards and at instant speed many of our creatures perform neat tricks.
Update:
It turns out that I had some extra cards in my collections from a while back so I've made these changes to the decklist because I already had the cards. They make this list less budget so I'll leave the changes below.
1x Recollect -> 1x Eternal Witness - Eternal Witness can be cast at instant speed with Yeva and can be bounced and replayed since it's a creature. It's a strict upgrade over Recollect for Yeva.
1x Llanowar Elves -> 1x Cultivate - Cultivate is one of the more costly ramp spells so it didn't originally fit in the budget but it provides more value than Llanowar Elves by giving two lands.
1x Meteor Golem -> 1x Beast Within - Beat Within costs so much less mana than Meteor Golem which makes it so much better since it becomes way easier to play. We already have Terastodon as tutorable non-land destruction so having everything destruction for 4 less mana is a great upgrade.
1x Elvish Mystic -> 1x Sakura-Tribe Elder - Again Sakura-Tribe Elder was out of the budget originally but it's way better than Elvish Mystic for putting a land rather than a creature onto the battlefield. Plus Sakura-Tribe Elder can be recurred through the graveyard.
1x Indrik Stomphowler -> 1x Bane of Progress - Bane of Progress is so much much much better than Indrik Stomphowler it's not even funny. We run NO artifacts and only a few enchantments so the fact that it destroys everything rather than one is an amazing upside. Since it costs 6 CMC instead of 5 it can be tutored with our Fierce Empath and it can be an amazing beat-stick and board-wipe all-in-one.
1x Werebear -> 1x Selvala, Heart of the Wilds - Somehow I happen to own a copy of Selvala, Heart of the Wilds so it upgrades Werebear by providing way more mana per activation and also has the benefit of drawing us cards since we are probably going to be playing the biggest creatures at the table.
1x Wave of Vitriol -> 1x Rishkar's Expertise - With the inclusion of Bane of Progress as tutorable, instant-speed artifact and enchantment destruction Wave of Vitriol is entirely unnecessary so we can remove it in favor of Rishkar's Expertise which is a great draw spell with the upside that we can cast something else for free after casting it. Most of our deck is 5 CMC and under so Rishkar's Expertise should allow us to play almost anything else we have in our hand.
1x Restock -> 1x Nissa, Vital Force - This may be a bad replacement. I'm not sure. But now the deck has a planeswalker which is neat. And Nissa, Vital Force also does recursion with it's -3 ability so it's not an entirely awful replacement. Basically it's only 1 card back from the graveyard instead of 2 with the added benefit that it's actually a planeswalker and can do other things too.
1x Call of the Wild -> 1x Eldritch Evolution - Eldritch Evolution is a tutor effect so it's better than the card advantage effect of Call of the Wild. Removing a creature from the deck doesn't feel great but I'm not sure what would be better to replace for Eldritch Evolution.
