Creskol is correct. Your button is shown in the Albert button-book, in the (US Government) Official and Diplomatic Service section as button OD-5. That book says that in addition to US Government Official/Diplomat use, OD-5 may have also been used by US Navy officers. The backmark is listed as "Strong Gilt" and the button is 25mm (i inch) in diameter. Your button dates from approximately 1810-to-1830.