They're one of the simple things I love to see show up at a new site... because here that means there's likely a decent military button to come, and possibly a Spanish silver too. Like seeing a George II copper as a sign also, but the button is a better one!
The range of these fall mostly in the 1750-1780 range. Although this is the British manufacture date & it might mean a few years on top until they came over to the US. The reverse of fashion today, ie. takes a few years for your stuff to reach us...lol
Even with our rich history, I never mind finding a good Dandy Button.