I agree with Crusader. Far more likely it is a contemporary counterfeit George III and as Cross Potent says, likely 1775. They made them thinner and thus more likely to get bent as yours appears.
Look at it this way..
There was a ton of counterfeiting going on in those days. It's almost impossible to tell.. but even if it is, it's still over 200 years old! It was certainly used as currency. It's still a very neat historical find. Enjoy it!
The same time or shortly after the coins they were copying. Many were shipped out from Britain, but many more were made in the US, which makes it more personal to your History.