Thanks for the replies and the information, everybody. Since that first post, I've found more. Most at my house, two of them from old foundations.
There are alot of different sizes.
It looks like a .45cal. I muzzle load in Ohio and I have a bag of these. They have made these for quite some time so being the depth you found it and not really knowing what kind of Wind and rain and soil you have, It could be 30 years old + or -