I've had similar thought as I've done my seed searches. There are a lot of things I find that fall, cultivation wise into that nebulous area called "famine foods" Most are small, and bitter. Several are actually poisonous in large enough quantities, the classic example of this being grasspea (Lathyrus sativus) and most of the vetches (favas excluded), or require complicated leeching processes to make safe to eat, like the older or darker seeded versions of a lot of tropical crops, Lablab bean for example (most of the WHITE seeded strains have seeds that can just be boiled and eaten as is, but eating the dark seeds usually requires a system of grinding and leeching to get rid of enough cyanogenic glucosides to make them safe to eat). I've often wonder WHY ancient farmers would bother with planting such things. Why not save their field space for "easy" crops. Why not pre select for strains that require no cleaning processes? Then I realize the reason is that these things are known to keep growing when conditions turn too hard for the "easy" stuff. Grasspea was (and in some places still is) grown because it is incredibly drought tolerant, and the desire to keep being fed when the rains come late far outweighs the risks of having your spine destroyed by Lathryism (which normally only comes if grasspeas make up more than 60% of your diet for several months anyway, so theoretically can be avoided if you are smart and budget your "good" crops in such a manner that the grasspeas become a way to stretch them, not replace them.) Bitter semi poisonous strains that need leeching are worth it, if those poisons mean your crop wont be devoured by insects or other animals (or why South American natives still grow bitter cassava, even though "sweet" (cyanide free) strains have existed for millennia.
Surviving often means not just pursuing your best advantage, bug figuring out how to also pursue ALL your other advantages at the same time, so you have a cushion to fall back on.
