Electroplating is easy to do similar to electrolysis. A guy I knew took about 20 pennies one day and nickle plated them. They come out nice a silvery looking. I play a joke on some telling them they are they new steel pennies like the war time pennies of the 40's. With the new coins out now they usually believe me for a while. This could be similar to what you have. It is still a very unique and interesting find.
Hey, I have one of those only it is a 1953 wheatie. I also have a gold plated bicentennial quarter both found at different times in different pieces of furniture.