I think knowledge is always lost and rediscovered.... We went a way from eating greens as a society in general but we are rediscovering them as an excellent source for nutrition. With the exception of spinach.... But nutritionally spinach give us nothing nutritionally till its cooked.
We as a family never gave up our southern roots.... Mustard greens I have gathered from the hills on horse back when I was a kid. Right here in San Diego. We ate and still eat Okra the favorite in the family is Breaded with corn meal and fried. But dad liked Okra Stewed tomatoes and bacon crumbles in Grits.... For dinner.
Fried Tripe too was a fav though I haven't made it in a while... Boiled till the flies come knocking on the screen door saying open open open, then chilled down and cut into strips. Roll those in cornmeal and fry them in Bacon grease..... served up with side dish of greens and I am in heaven. That's a meal that costs next to nothing even now.