Has all the signs of being from the “golden age” of gilt buttons. 1830’s-40’s.
added: if someone has time to look it up it’s likely a Leavenworth backmark from what I can see.
If the backmark reads Leavenworth & co. it dates from 1839-49. My guess is it would date much closer to the 1839 period due to the fact that it is a 1 piece button. Is there more to the backmark than Leavenworth & co.?