Are you sure it's tin? Looks like oxidized brass. I've dug hundreds of these 'one piece' buttons here in Virginia. We refer to them as 'flower buttons.' I realize there is no flower but many had flower patterns. I've also dug ones that looked like a Chinese Checker Board, spiral patterns and numerous other designs. Probably dates back to the early 1800s to 1850's. Could be earlier too but many of the very early buttons had a 'bird cage' shank or 'turret' shank. Too bad it wasn't military.




















