Saab Making FUnny Sound

My 2001 9-5 Saab is making a rattling noise in what sounds like the front wheel. Only when it starts up and for the first mile or so. What is it?

In the old day of hubcaps this would sound like a lug nut came loose and was rolling around in the hubcap until speed and centrifical force would make it go quiet.

To be safe you need to get this checked out by a mechanic.