It had been several years since I last found a Civil War uniform button, but I found 2 this month.
Looks to be a general service button. No back mark.
https://i.imgur.com/k7M9cVS.jpg
I got excited when I dug the remains of a coin purse, but no coins to be found.
https://i.imgur.com/5iHF8mC.jpg
Jeff