if much of anything happens, a complete collapse will follow. the game, fish and known edible wild plants will be gone in a couple of months of any such collapse. nobody is going to be living off of the land, other than by being a cannibal. you can easily, however, live off of sprouts, potatoes grown in buckets, and similar stuff. Youtube is full of videos about that. openly revealed garden plots will get you raided/sniped. so they're not feasible, for at least a year after shtf, and even then, good idea to have them in the middle of a thicket, on a hill top