Showtime2385, I had more info to add, but a phonecall made me have to post what I'd written or lose it. Here is the rest of what I was going to say.
As the info posted by Crappies-n-Coins shows, the button is NOT a high-dollar-value Revolutionary War "Continental Army" button... it is from the early-1800s which makes it a US Army button, probably in-service during the War-of-1812.
The reason there are many minor variations is that the US button-making industry was in its infancy. Brass for buttons was scarce because the British were still restricting exports of that metal to the US, to protect the British button-making industry. The post-Revolutionary-War US army was quite small, therefore needing only relatively small quantities of buttons. Orders for new or replacement buttons tended to come years apart. American button die-makers could not yet match the quality of British stamping-dies. The American stamping-dies wore out, or broke, and often it was cheaper and simpler to make a new front-die (and backmark die) when the army finally got around to ordering another batch of buttons. Put simply, in that very-ealy period of American Military button-making, minor variations in the design were the rule, not the exception to the rule. Even the Albert button-book doesn't show all the known minor variations.
