Yep a New York button. The backmark is probably extra quality which can go into at least the late 1800's. From the pic I think you button is post civil war because of the detail on the face. It might help if you could post a pic of the back. Nice civil war NY's go for $20 - $25. Post war a lot less $2 - $5
CURRENTLY USING: Minelab Go-Find 60, Nokta Fors CoRe, Macro Racer, Whites MXT All Pro, Fisher F19, Garrett AT Gold, Minelab CTX3030, XP Deus.
USED: Garrett ATX, Garrett AT Pro, Minelab E-Trac, Minelab