Bristlebud Farmer
is good on many levels. First its stats, being a 4-cost 5/5 trample with no disadvantages. Second, its ETB trigger, creating not one, but two foods when it enters is just a great bonus, which leads us to its third
thing, which is really nice card advantage, especially for a Gruul deck, because there's not too much black/green draw that's legal in standard.
Experimental Confectioner
gives a food when it enters and rats whenever you sac those foods, even when you sacrifice them to Greta, Sweettooth Scourge or Provisions Merchant. And the rats themselves can be really good, especially if they ar made to count as foods with Yrga, Eater of All, and the bunch of easy sac fodder is nice for cards like Old Flittering or the previously mentioned Bristlebud Farmer.
Greta, Sweettooth Scourge is just a create food ETB and an additional sac outlet that can get pretty big pretty fast, and another sac ability to draw and lose a life, so its just a nice card to have all around. I only included three in the deck because I always try to be cautious with the legendaries in my decks.
Intrepid Trufflesnout is a pretty nice card to get out early, and even if you don't find yourself needing the adventure all that much, the 2 MV 3/1 that gives a food as long as it's the only one attacking is good, and I find that the food can pile up pretty high.
Old Flitterfang really struck a chord with me as soon as I saw it in Scryfall, though, because it's not amazing, I have only included two in the deck. It'll give you a food whenever something dies, and it can do quite a bit to someone if their not careful because of the flying and ability to sac a food to give it +2+2.
Provisions Merchant creates a food when it enter to kick it off, and it'll give everything +1+1 and trample if you want to sacrifice a food, and you can easily overwhelm them using tokens with cards like Experimental Confectioner.
Scream Puff is a fun card. A big body first of all, deathtouch to dissuade them from blocking it, and a food whenever they don't block it, which, like Intrepid Trufflesnout, can give you mountains of food over time to sac for life or to another sacrifice outlet.
Tough Cookie is a cheap food creation ETB, it can make your foods 4/4s and can be used as a food in a pinch. Multiple times i've won the game with the sheer number of 4/4s you can make if you have the mana, and can win you the game if everyone's very late game, but too scared to attack one another in fear of a deadly retaliation, in my experience, happens often in more casual play.
Yrga, Eater of All is a silly, silly card. First of all it makes everything on everyone's board foods, and can get huge if someone kills a bunch of stuff, and to get rid of it they have to sac something to it's ward cost anyways.
Restless Cottage is in there because I wanted a BG land, and it creates a food whenever it attacks. It's the only land that enters tapped though, because this deck is already slow enough and too many lands entering tapped would make it even slower.
Night of the Sweets' Revenge is amazing ramp that also can give you a big anthem when you sacrifice it, and, even though, it costs 7 mana to activate it, mana shouldn't be a huge problem because of the ramp ability.
Scavenger's Talent is a nice 1-cost class that gives you a food whenever something dies, and once you level it up to three, you'll get big stuff out of you graveyard for sacrificing stuff, and getting cards in your graveyard shouldn't be a problem with its level two ability, especially because you'll (hopefully) be gaining and sacrificing multiple foods a turn.
