Flat button

[RustyRelic]

Found at cavalry site. It's got the gold rings on back. The front you can't make out anything, completely tarnished over. It's small and crude looking

 

[Cornpone and Molasses]

Colonial Flat cuff button?

 

[Joe Whitworth]

The two gold bands are all that remains of it's once gold plating. An amalgam of Mercury and gold was painted onto the button and then placed in an oven. Mercury was burned off leaving q gold plated surface. The amalgam was thicker in those slightly recessed areas on your button and have remained. YMMV