Interesting! Where would I look to find out more? Is there info in the internet? Whatever this is,it's been in the ground quite a while.
It looks exactly like the tin back button Indian war 4r24s-2p. Thanks a lot!! Any idea on age?The back of your button is rusted away .. or on the way to rusting away, which indicates that it is a tin backed button. Prior to the Indian War, all of them had a brass back and most carried a backmark.
Here is a educational site to visit.
This first link shows pre war thru the Civil War general staff buttons: Pre War ? Civil War Button Gallery | General Staff Buttons
This second link shows post war, Indian War & simulated: Post War Button Gallery | General Staff Buttons