Oh dear, I didn't realize that you already had them. Shipping them back would probably cost as much as the seeds.
What other seeds did the seller have?
Other than exchanging or trashing, the only other thing that I could think to do with them is to use them as part of some sort of craft or artwork using other natural materials like acorn caps, other seeds, seeds pods, etc.
The seeds also float which is amusing to see, as long as they are contained in a bowl on your kitchen counter, of course!
