This has to be related to the Department of the Treasury, yet even though there's an anchor it isn't from the Cutter Service, which also has most of the same elements.
It closely resembles a Revenue Cutter Service button as shown in the link. Maybe it is different because of the manufacturer. None pictured in the link have the same maker although there are a few Horstmann and Alliens. A little bit of trivia here: it was called the Revenue Marine service until 1894.
nhbenz too bad the picture in that forum was a little low resolution. It looks like a combination of the second and third on the top row. The second has no U and S on the either side (like the one I found) and the third has what could be 7 crosses on the chevron (also like the one I found). The best guess so far is the revenue cutter service but I wonder what year.