
It is a Livery button with a bird probably a heron standing on a crest/shield. Circa 1830s. Check this site for a match;I’d guess it to be a livery or family crest button, with a peacock? or stork? at the top.
I see a Marching band uniform button
https://www.demoulin.com/marching-band/replacement-parts/uniform-buttons/oxidized-crest-button-dozenView attachment 1601144