Dug this a few hours ago,!Looks and feels to be solid brass and found in an area where old homes were and Civil War action was seen. I'll most likely check in tomorrow morning,this ole gal is tirrreedd!
I should of called it a wedge clamp. A wire runs thru it and the harder it's pulled,
the tighter it grips. It's used where a wire enters a house or barn to take the weight
and tension off the part that goes into the house. Otherwise, snow, ice or wind would
pull the wire back out of the house. Your piece is what provided a grip.