South of I-40 on Country Club Road, on the way to the El Reno Airport, you can find this large, rectangular mailbox with night scenes of the mountains in the light of the full moon.
Just as Country Club road angles west to meet W 10th St, look to the left (just after the buffalo silhouettes on the right). I just parked off to the right on the grass, as there is no place other than that to pull off.