The duck,
Congratulations on finding an American military button in Australia!
Your button find is a U.S. Navy button, dating from the late 1830's through early 1850's. The button is of two-piece brass construction, with gold gilding. The design is a match for NA203 A. in
Uniform Buttons of the United States 1776-1865 by Warren Tice. Since there is mention of this particular button find being smaller cuff size, then it should be along the line of 14-15mm as listed for NA 203 As. with various backmarks. The backmark of "Waterbury" would in fact be the mark for; ' ' SCOVILLS & Co ' ' WATERBURY, in raised letter markings in a depressed channel (RMDC) on the button.
Kuger,
Your button is a variant of the same button design.
Listed as NA203 As. 7. with a backmark of ; ********************.
According to Tice, these buttons dies were in use from 1837 and into the early 1850's. Your date of 1845 is right smack in the middle of the time period. We can give or take a half dozen years and still be quite fair. Waterbury Button Company formed in 1849, and continued for nearly a century. To my knowledge, their backmark is not known on these earlier two-piece pre-Civil War Navy buttons, featuring an eagle on a vertical anchor. Their predecessor though, Benedict & Burnham, are noted with their backmark on similar styles of Navy buttons of the period.
CC Hunter
P.S.While I was checking facts and references, Prof. CannoballGuy was already typing away a factual reply.
Alberts #NA-102 is indeed correct as well and the earlier listing for this button, which translates as NA203 A. in Tice's later expanded work. Alphaeus Albert though, only listed the larger 22mm size at the time of his publication.