Hi~I found this in 2002 in the garden spot that once was used to grow various crops of tobacco, corn, hay, etc. Field has been in use over 200 years. It is completely round, smooth, weighs one oz. Sounds like a rock when tapped against something. Color is white-grey. One idea was thought the object may have something to do with the Civil War. Within a five mile radius of the area there has been grist mills, Indian tribes, farming, railroad, hunting, blacksmith shops. What is this?
I know my Grandparents had a round rock about the size of a basketball that looked alot like yours. They told me it was rounded by glaciers rolling across it but Grandpa was known for blowing smoke now and then... That's my best guess anyway.
At approximately 1.25-inch in diameter and weighing one ounce, its size-versus-weight ratio strongly indicates it is an antique baked-clay marble, most probably from sometime in the 1800s. Do a websearch for "clay marbles."