I used to eat corn mush too and I loved it as a kid and find it a comfort food as an adult. My husband looks at me like a nut when I make a cake of cornbread, smash it up in a bowl and pour milk over it.
I've never seen livermush sold here. Doesn't mean it isn't - I just haven't seen it. Then again, I don't eat meat anymore, so I'm usually not in the processed lunch meat aisle.
It's a gray block of liver mashed with cornmeal, almost like a pate texture, pre-cooked and served in a block that looks remarkably similar to scrapple but they do not taste the same. Wikipedia says it is a Southern Staple.
So I guess it's a regional thing.
Livermush - Wikipedia, the free encyclopedia
But I think the below article describes it a bit better (I had no idea there was a Livermush Festival), and since I spent my childhood being shuffled between NC and GA, it makes since that I remember this fondly as only being eaten in the summer. I used to have it cold (it's pre-cooked) and smear it on bread with mustard with some potato chips, cola and a dill pickle. Ahhhh the memories.
Unusual Southern Foods