It can be pretty difficult to find artifacts still in decent shape in most creeks here in middle and east TN due to the loose hardstone rock beds. I believe what you have found appears to me to be a piece of limestone. Being found in a creek and the looks of material, the chances of being an artifact are pretty slim imo
If you see any tilled soil on a nearby knoll, then that might be a good place to check as well.
Now when you search on the west side of the TN river the soil becomes much more sandy and they find some killers in the creeks there that are in excellent shape. Maybe in your area you can look at the banks on the side of a creek where erosion has occurred exposing where once was habitation, typically layered in darker soil.
Good luck, be careful and Im far from being an expert so take my help with a grain of salt.