Brass 1-piece flatbuttons with a backmark written in indented lettering were manufactured from about 1810 to about 1840. We can narrow down the date of your dug-in-America flatbutton with a few historical facts. The spelling of the word "color" on your button is the British version, "colour". The War Of 1812 (US versus Britain) interrupted trade between the two countries, and the resulting postwar American patriotic distaste for British-made products minimized importation from Britain until about 10 years after the 1815 end of that war. By 1830, the American button-making industry had become capable of producing enough to supply the demand=level from American button-customers. So, the statistical odds favor your button being imported into the US sometime in the mid-1820s through late-1820s.
