The shellbug helmet and the weird bird skull amulet I can't remember the name of. I haven't a clue.

You get the shellbug chitin in random falmer caves in the Forgotten Vale, they're giant cute lil' fellas that are usually hiding in hidden crevices in the caves, you can mine them.

For the Bone Hawk Amulet, simply kill the birds flying around Castle Volkihar.