Here's something I learned yesterday:
It was common in the past for farmers to buy up old clothes by the cartload and plough them into their land as fertiliser. Inevitably quite a few of the garments still had buttons attached- which is why detectorists find so many.
And of course some of the old clothes would have had things in their pockets- like coins. It occurs to me that our two musket balls might have reached us in the deep pockets of a discarded military greatcoat.