It's a Museum of Neberaska History mug. (i.e. museum maintained by the Nebraska State Historical Society, of which I am a life member). It has Pawnee dancers on it.
i painted mine. my girlfriend wanted to go to a pottery place where we painted our own cups and stuff, so i filled mine with inside jokes between me and my roommates
Oh my gosh i totally forgot! sorry lol i have this, it's not a coffee mug, but i got it from starbucks so maybe it'll do :) i'll get you a real mug next time i go. i go there all the time so it shouldn't be long :p