Button Help.

[Garabaldi]

I have found the Great Coat button before, which is in the Alberts book, but I found two buttons that have teh same US mark on them, but are not in the book. Any ideas on these two? I found them at a old military training post. One of them have been modified with a square notch through it. I found what I think is a musket ball with the same notch. I suspect the musket ball was used for a fishing weight. Any ideas about the buttons? The reason the two buttons are different color than the US Great Coat button is that they were found in clay, which preserves them better.
Thanks

[Garabaldi]

I actually found it in the Alberts button book. They are "Army, General Service; cast pewter, 1 Piece. 1808-1830"