Hey man how's it going...I'm from middle ga and my wife and I walk creek beds and we have found pieces almost exactly like urs...we too pick them up with our thoughts being it's bought got to be man made shapes like that....and honestly from my 12 yrs of experience, I would say it's something, and is there anyone who can say 100% they know it's not
Natural imo. Try looking in the fields for them much easier to know when they were used. The creek water will remove the grinding if they were ever used.