rattle under back seat

["Steve Nash" <nashflr@erols.com>]

Gruppe,

My Jetta has developed a strange rattle or buzz under the rear seat area.
It sounds like a plastic on metal type of sound.  It is both temperature and
engine rev related.  It is only heard on cold mornings when the car is first
started.  After it warms up it will go away.  It happens mostly on the 1st
to 2nd shift.  Have any of you fellow Jetta owners experienced this before.
Please help so I can get my wife off my back:)

Steve Nash