Soviet Kitchen has lots of recipes on how they ate in the good old days, including Boiled Brain
and Lamb Offal cooked in a skillet.
such things are not usually eaten in the USA, but in countries where there is not a lot of meat one can afford, poor folks tend to eat what ever is available.
So Chitlin's is a well known soul food.
Here we often have liver/kidney parts in the soup, and often the local dish Tsunomis is made with pork, liver and pork blood coagulated, however our cook usually flavors it with sampalok leaves, which makes it sour.
We also make kare kare with stomach instead of ox tail or beef...
The Manila Bulletin article here discusses the omnivorous Pinoy's ability to eat the whole thing, and includes a list of a lot of local delicacies.
Not mentioned: Fish heads, which here are a delicacy to have the goodness sucked out of them, not discarded in the garbage. And Yes, I eat liver, tripe etc. but not fishheads or crickets.
And from the land of steak and kidney pie: The BBC's Offal recipe page.
YUM! The Great British Faggot!
and yes, you can even buy frozen faggots: