My Oldest US Coin

This is (was - updated below) my oldest American coin. I found it in Jackson Park in Chicago in 1979, near the museum of Science and Industry. It was obviously worn on a chain for a period, then some uneducated soul thought it would be fixed and they could get more for it if they filled the hole. It looks like lead in the hole. It's hard to say when it was dropped, but the even green patina indicates it was in the ground for at least 50 years. I thought I was doing great, and my brother exclaimed, "You lucky sucker," when I called him over and showed him, but a few minutes later he found a 1792 Mexican silver coin a little larger than a dime a short distance away. That made him feel better. 

I have a new oldest coin used in the US!  It is not US minted, it predates that as a coin used in colonial times.  The post to the Treasurenet forums explains it all!  The message title is "Thanks Hoover Boys", and it is found here;

Thanks Hoover Boys 

I didn't realize what it was for over 20 years as explained in the Treasurenet post.  I believe I found it somewhere in Connecticut during my trip out there.