I found a 20ga pump, while on a duck hunt, just a couple of weeks ago. The barrel and receiver were buried in the mud, but the buttstock was visible in the water. The gun had a shell in the chamber and magazine, but we could not get the action to open.

It was on a public duck hunting property here in Colorado, (Andrick Ponds), which used to be my coyote honey-hole when John Andrick owned it and ran it as a private duck hunting club.