This isn't the best photo, but this keystone is high up on an historic downtown building featured [here] and I had to take it from across the street. It holds a representation of the $10 gold piece "Beaver coin", minted in 1849 by the provisional government of Oregon. The Beaver money was used until the establishment of an United States mint in San Francisco, when U.S. gold and silver coins made their use unnecessary.
On the front side of the coin above the beaver were the letters "K.M.T.R.C.S.", the initials of the group of men who purchased the machinery, made the dies and minted the coins. Beneath the beaver, "O.T. 1849." (Oregon Territory). Oregon became a state ten years later.
A couple years ago one of the $5 coins was sold for $125K. [Read Story]