The 17th Infantry Regiment was organized on January 11, 1812, thus the date on the nickel. The buffalo, shown on the blue shield below the stone wall represents the Regiments glorious history in the Korean war. The "Buffalo" nickname was adopted after one of the Regiment's Commanding Officers in the Korean war, Col. William W. "Buffalo Bill" Quinn. There have been 18 Medal of Honor awards to soldiers of this regiment over the years since the start of the Spanish American War.

Thanks to Wikimedia for the above historical info.

Soldiers with lots of time on their hands have been known to make mementos out of battlefield scrap like brass artillery casings. That could be what your piece is.