They will really perplex future archaeologists finding them in a peat bog.
I can attest to this problem, working at a National Battlefield with has living history programs in summer with reenactors and park volunteers & staff. We actually have an area of the battlefield specifically designated for such programs which has already had several major digs to ensure that any dropped musket caps, friction primers from artillery pieces, uniform buttons, etc. used by reenactors are not mistaken for the "real thing".

Cheers,

Todd