I have a bag of dehydrated eggplant slices that I brought back from Italy. Do I have to rehydrate them first? Any recipe ideas?

Humm.. I'd try them with a variation of Amanda's mushroom salad.
Just a slice or two test.
http://www.food52.com/recipes/10551_button_mushroom_salad
With a low, very low heat in the olive olive until they soak up the oil.
Then a bit of a higher cooking. And some crusty bread, naan bread, or lavish bread, or toasted pita.

Definitely rehydrate in hot water to cover until tender. How did you get them through Customs?!