I'm a sucker for organs, we eat kokoretsi or kokorec like our Turkish neighbours say it. It contains lamb organs, intestines, heart, liver, lungs, sweet breads (from Thymus and pancreas) and lamb suet. It's delicious af but it's full of fats so i eat it maybe 6-7 times a year. I like the head too, brain, cheeks and tongue.
For bb purposes beef liver is my way to go, usually cook a decent portion of like 1-1,5kg and put it in the freezer at 80-100gr ziplock bags. I prefer eating small amounts as an addition with other meals and not so frequent due to its very high vitamin concentration. It's a great source of heme iron though.