Butterbeer cork necklace

Butterbear Cork Necklace
Luna Lovegood,a Ravenclaw student, has a Butterbear cork necklace that she wears, that everyone find particulary weird. She also has a pair of Radish Earrings.

The Film
In the Harry Potter Order of the Phoniex (Film), the actress playing Luna Lovegood Evanna Lynch wears a Butterbear Cork necklace with just one cork on it. In the Films she claims it keeps off the Nargles(a creature she belives to be true).