What don't we eat anything which is edible?

Another readable book that discusses issues like this is The Sacred Cow and the Aboinable Pig (aka Good to Eat), by Marvin Harris. I’m sure there are more recent books that discuss the sociology of food like this, but I haven’t really looked for them.

As noted before, it seems to boil down to the food value of the item vs. how difficult it is to acquire.