A lot of people used to eat brains...beef brains, pig brains, I don't think chickens have brains.

Modern Standard American Diet of the past 2 generations changed that.
Small old time farmers were known to use about the whole carcass, kind of like the poor indians.
Now there's Mad Cow Disease that makes it illegal in USA to sell the head IF I remember correctly.
Some say its a hoax. I've not been convinced one way or another.
One thing fer sure. The junk big feed lots feed cows is shameful and the meat processing plants will turn your stomach even if you butchered a hundred deer.