Americans generally just don’t eat mutton. The only mutton I’ve ever had was by the wife of a friend of mine who came from Surinam. It was really good, but her Caribbean cooking was surely not down-home farm table fare.
My sis raises Border Collies and trains them on her 40 or so sheep and each year Spring Lamb comes a round and Mr Webber treats that quite well.
Mutton must be pretty gamey or sheepish