From AI:
A 40mm patinated copper button with 13 intentionally cut sides, a slight dome, and a shank remnant is an exceptional and highly specific artifact from the American Revolutionary period (c. 1775–1783).
At 40mm (about 1.5 inches), this is known as a "Dandy Button." These were oversized, flashy buttons popular in the late 18th century, typically worn on the heavy outer coats of high-status individuals or soldiers emulating aristocratic fashion.
Why it is "13-Sided"
Finding a button of this size with exactly 13 hand-cut sides is extremely rare and carries deep historical weight:
- A Patriotic Act: Standard Dandy buttons were round. The fact that this one was hand-filed into 13 facets suggests it was a deliberate piece of "Trench Art" or Folk Art. During the Revolution in New Jersey, the number 13 was the ultimate symbol of the 13 United Colonies. A soldier or a local citizen likely customized this button to display their political allegiance.
- The Dome Shape: The "convex" or slight dome shape was a classic feature of late 18th-century copper alloy buttons. This design added strength to the large face of the button and helped it catch the light, making it a "flashy" statement piece.
Identification: Modified 18th Century Coat Button
- Original Form: It likely started as a large, round, flat or slightly domed "Tombac" or copper alloy coat button.
- The Shank: The wire shank remnant in the center is a diagnostic feature of 18th-century construction. These were often cast or brazed directly onto the back.
- Patina: The "crusty" green or dark brown surface (patina) is the natural oxidation of copper after spending over 200 years in the acidic soil of New Jersey.
njenjoy.com +4
Possible Secondary Use: The "Whizz" Toy
If the shank was broken or intentionally removed to create the central hole, it may have been repurposed as a "Whizz" or buzz-saw toy. Soldiers in Revolutionary War camps often took broken buttons, faceted the edges to create a "whirring" sound, and spun them on a string as a way to pass the time.
This find is a remarkable "crossover" object—part functional garment fastener, part political statement, and potentially part wartime toy.
But when the weather breaks, and if I am able to, I hope to go out and try to find some of them. It has been a long while. 
