Cold Digger,
Your button find carries a design that appears rather familiar to my eye, being one that quite certainly has been dug among the thousands of buttons excavated over the past thirty years or more. I believe this is in fact a low convex two-piece brass button, dating to around the late 1830's through 1840's, being manufactured by one of the principal American companies based in Waterbury Connecticut, such as R.W. Robinson, W.H. Jones, Scovills, or Ives, Kendrick & Co., and others. The design of 16 closely spaced dots within a detailed background, is quite distinct and falls within the various design patterns noted to be of a popular style during the era of "Golden Age" buttons. These Golden Age buttons of the earlier 19th Century exhibit a degree of die work and manufacturing detail rarely seen in later years, as mass production and cost-cutting techniques took precedence over the eye pleasing work seen earlier during the pinnacle of quality button manufacturing.
CC Hunter