Key

The key is the mechanism of the powers of opening and closing, and denotes liberation, knowledge, mystery, and initiation. Silver keys usually refer to temporal power, while gold ones refer to spiritual power. In Christianity, it is the emblem of St Peter as the guardian of the gate of heaven, and the key may either confine or release.    Information taken from:   Online Symbolism Dictionary

Your unconscious is offering you access to your true identity or a solution to a problem.  From - Dream Dictionary.

  Songs referenced: 

Cornflake Girl

Little Amsterdam
(underlyrics)