It's walnut alright. Made ca. 1860. Beautiful, although unfortunately the form is pretty common. It could very easily have been made in the midwest, maybe Ohio or Michigan. Actually, it could have been made anywhere in the northeastern U.S.
The mirror frame may or may not be original (I think it is) but if not, the one the dresser has now is perfectly appropriate.
I don't know where you are, but in Missouri USA it would probably insure for $500-$750.