One of Got2dig's two guesses is correct. It is definitely a sword scabbard-hanger band. Part of your band is broken off at the screw-hole. It could be from either a US Model-1850 Foot-Officer's sword scabbard, or a US Field-&-Staff Officer's scabbard. The Confederates also manufactured some like it. Therefore, I cannot tell you which specific version you found. So I suggest that you take your scabbard-hanger band to some civil war relic shows and hunt for an EXACT match on various non-dug scabbards. The width of the band and (in particular) the exact shape of the knob which held the brass ring, and the ring's precise diameter are the ID-clues to try to match. Here are some photos on non-dug ones.