It is a brass 2-piece civilian "Fashion" button with a raised-lettering backmark, which indicates it is from the 1830s through early-1850s. That time-period matches up with the employment of William Eaves as the chief die-sinker & buttonmaker for the firm of JML & WH Scovill of Waterbury CT from 1829 to 1842. After Mr. Eaves left the Scovill firm, he had his own company from 1842 to at least 1852. The additional letters in your button's backmark after Mr. Eaves name might be "& Son" or "& Co" -- which indicates it was made when Mr. Eaves had his own buttonmaking company. The timeline information (and more info about Mr. Eaves) is in the book "American Military Button Makers And Dealers; Their Backmarks & Dates" by William F. McGuinn & Bruce S. Bazelon.