Welcome to the forum, Henry.
I think the patchboxes held pretty much whatever the owner wanted to put in them. On rifles that I have or have had, there's been round balls, bits of patch material, the residue of some sort of lubricant, ramrod extensions with a worm, fuzzy lint sort of stuff I suppose for cleaning the gun, percussion caps for those guns, and a friend has a gun with the price of the gun scratched into the inside of the patchbox door....
John