Well - it's a beautiful guilted General Service Eagle Button! Man what a looker! It appears to be made in the "muffin" style... These eagle buttons were the norm until 1902 when the U.S.Army adopted the current style - the U.S.Army Great Seal Button.
It's possible it saw action someplace but there is NO way to tell... for example, is your backyard a CW battlefield? A skirmish site? A training camp? A military camp of any kind? With no clues as to where you live it's kinda hard to tell... well, impossible to tell who lost it. Did a CW vet live in your house?
Also - the only way to date your button is to see the back mark... what's written on the back?
tell us what it says on the back and also count the stars around the front that will help us with the age and what exact button it , because there were alot of varieties
I think it has 28 stars on it. It says Horstman & Co on the back. I live in a small town west of Minneapolis. The house I live in was built in 1907 but I know there used to be older buildings on my block including the one from the town's founder in the 1800's.