Ok, about 1.0 to 1.5mm thick. Scaling picture its about 31mm diameter.
Could be an early British half penny. These are thinner than the US large Cent:
https://www.predecimal.com/british_coins_identification
https://en.wikipedia.org/wiki/History_of_the_halfpenny
Next is measure the weight and compare.
British half penny are about 10gram
US large Cent are 13.4 gram.
Corrosion will reduce the weight.
Possible this coin is of other foreign mintage.