First 2 photos are in unenhanced indoor lighting; third photo has contrast and shadows turned up to show details; fourth photo zooms in on the little letters by the hole; last photo is of the all but erased back that still shows seated Britannia’s outline. 

I know whatever it is, it isn’t worth much because of the drilled hole on top of how badly worn it is, but the mystery of What Is It is really bugging me. 

Best match is a 1750s era British George III half penny, but the head outline seems wrong (even if badly worn) to match all the stuff going on in his half penny portrait. I can make out GEO(R?) on the left side of the portrait, but there is also an upside down ?T-R? to the left of the hole that I can find no examples of anywhere. The back is badly worn, but the outline of Britannia is still clear. Any date mark is lonnnnnng gone. 

It weighs roughly 8oz by kitchen scale (I can’t seem to find my jewelry scale, ugh) and is \~27mm in diameter (I may be off 1mm in either direction). It is thin from wear and maybe 1mm thick. 

Is this just a really old counterfeit, or…?

FTR something British or colonial would make the most sense considering the rest of this inherited collection, though we ARE finding random 1800s coins from Spain, Sweden, Greece, Brazil, Ottoman Empire, and Canada. 

UGH Waving the white flag on IDing this old copper/bronze coin—HELP