The second nut hickory?Hickory?
No, it's definitely not a walnutThe darker one looks like a walnut. But they are in a green round pod when they are on the tree, as they ripen it turns black. someone or thing, squirrel probably, would have had to peel it out of the ripened pod and then put it in the tree. Not sure of the lighter one. Btw, I thought you were going to have someone's picture posted
The second one looks a lot like a hickory nut! ThanksHickory?