I can tell you more about the backmark when I get a minute to grab my backmark book, but I can tell you that it is a civilian button cira 1830-1840s
Congrats!
According to my back mark book M.S. & J.D. is an unidentified maker or dealer, probably English. It has been found on military buttons but, like Dan said yours is a civilian one. Still a nice find and great pictures to aid in it's ID.