I'm guessing the only place you can find bison in Oregon is on a feedlot. Cattle ranchers haven't been too excited about the idea of a land where the buffalo roam because diseases they sometimes carry can infect cows.
Liver, tongue and hump meat are some of the best eats you'll ever have. Everything else makes beef jealous, but those three are yummmmeeeee. That hump meat has the most fat in the whole buffalo, tender, juicy, full of flavor.