First... I see that's your very first post, so... welcome to TreasureNet, and the What Is It? forum, which is the best place on the internet to get unknown objects CORRECTLY identified.
You didn't include a photo, but from your description I'm sure the object is a brass 1-piece flatbutton. The British spelling of the word color as "colour" means it was made in Britain. In the very-early 1800s, millions were imported into the US because the young American button-making industry could not supply enough to fill the demand from clothing-makers. They were used on civilian clothing, although we know a few did get used on Militia uniforms.
If your brass 1-piece flatbutton's backmark is written in raised lettering it dates from about 1790 into the 1830s. If the lettering is indented, it dates from about 1810 into the 1830s.
These plain-front brass flatbuttons fell out of favor with the public in the 1830s, and pretty much stopped being manufactured, due to the advent of inexpensively-priced "ornate" 2-piece brass buttons.
..Sorry couldn't resist, do you have pictures it appears you forget to load them.
