I have a friend and neighbor (about 1 mile away) who has his back yard all torn up, as it turns out his 3/4 acre property was a campsite for Union soldiers during the Civil War, and by coincidence he's a major league collector and finder (ie metal detectors) of such trinkets. He's like a kid in a candy store. But they had to be turning up all kinds of stuff when they built his house.
The history of this area during the Civil War presents an interesting dilemma. Much of northern Virginia was scarcely occupied at the time and those that did live here left the area when the Union soldiers took over the territory. So, many accounts of the war in places like Sully, Herndon/Frying Pan, Ox Hill/Chantilly, Vienna, Sterling, etc., are reliant on the writings of the individual soldiers participating in the battles. Unlike other parts of the war, though, much of the warfare in noVA was guerilla style and therefore was left blank in the pages of the soldiers that participated. I believe it was only a few years ago that a local scholar (Charles Mauro) pointed out the importance of the battle of Chantilly/Ox Hill, which had been virtually neglected until then. Through my own research, I was able to highlight the importance of the old Frying Pan Meetinghouse/Primitive Baptist Church to the Confederacy/Union troops during the war. Surprisingly, for all the Civil War history in VA, northern Virginia is largely overlooked.