It looks to be in to good of condition to be weather worn or from being in the ground but I just dont know.....???
Missing Clad Layer usually occurs on just one side of a clad coin. You will see the copper core on one side and the other side will look normal. Here are examples of 2 that I own -
Now Environmental Damaged on Clad coins are plentiful. Even if the coin looks to be in good condition, such as yours, the Clad layer can be affected. I metal detect and I have found hundreds of examples of Environmental Damage. Here are some that I have found -