What dose Hermes give to Odysseus to protect him from Circe's Magic?

Hermes gives Odysseus a magical herb called "moly" to protect him from Circe's magic. This herb has a black root and a white blossom, and it is said to be extremely potent against enchantments and sorcery. With this protection, Odysseus is able to resist Circe's spells and ultimately confront her effectively.