Your find is definitely the "tongue" component of a Ladies Patriotic Sash Belt, from the very late 1800s. Those belts typically consisted of various Military Emblem button fronts crimped over a loop-less button back, connected with each other by four interlocking rings or tabs projecting from the sides of the flat brass disc back component. See the photos below.
Your find, showing the number 71 inside a wreath, represents the New York State Militia's 71st Regiment. (Shown in the Albert button-book as button #61b, page 207.)
I should mention, almost every such belt I've seen thus far consists of US Army, US Navy, or yankee State Seal buttons. One exception consisted of Musician's button-fronts. The other exception is, I've seen only one of these button-front belt links which shows a Southern state seal. Please note, all of the State Seal button-fronts show a post-civil-war version of the seal. Therefore, they seem to have been manufactured in the very-late 1800s (1880s-to-about-1910) and sold for use by yankee Veterans' wives and daughters.
