CW service marker found

Well i had a very slow day as far as good stuff today.mourning hunt got me a hood ornament and a wheat cent from a few old foundations.Along with a pile of brass and copper ,and a heavy aluminum pot for the scrap pile(save it for batteries,last pile was $18.00 not bad for 2 weeks of crap)Then hit a tot lot.All i got their was clad.I was pretty whipped so took a break till 6 then went back out.And hit bank next to creek.It is very steep and a bugger to hunt but i always seem to get odd stuff.Usualy mostly junk for scrap pile but 1 or 2 keepers.Today was no different.Got a badly worn lead seal of some sort.And my best find of the day a CW grave marker for service in the war.Front says GAR 1861-1865.Back says"presented by the county comissioners sunbury pa"I am not sure what gar means.but i know a service marker and date when i see one.Their is a small military section of grave yard above my house.This would be about 10 blocks down creek from where i was hunting.(was in woods,5 feet from creek)guy down street knows one of the caretakers for graves and is checking with him to see if one stars is missing.their is a grave dump below cemetery but this was way up creek from it.Hopefully i can get this back to ritefull place.Unless of course it was replaced.