In case you don't already know... button-collectors call that type of button a brass 1-piece flatbutton. Yours looks like it has a backmark (manufacturer's marking on the button's back) with indented lettering, which if seen on a ONE-PIECE brass button means it dates from approximately 1810 into the 1830s. That rather plain-looking type of metal button quickly fell out of favor with the public when machinery was invented which enabled button-makers to inexpensively mass-produce "fancy" 2-piece brass buttons, in the early-1830s.