When I was a boy, My elementary school cafeteria would?

My elementary school cafeteria would often serve Hamburgers. Does anyone know?

My elementary school cafeteria would often serve Hamburgers. Does anyone know what the mixture of ground beef to oats and eggs that were added to stretch the meat? And also the mix of ketchup and mayo with relish... I wanted to see if this would be good enough to reduce my LDL colesitrol