Formula: Nothing, the interior is kept clean at all times.
GTP: Son's coat, a snow brushy thing, a keyboard, some Xbox 360 stuff Thorne will never pick up, the cover to the OnStar module mounted in there.
Silverado: Doesn't have a trunk. The rear seat of the cab has two new rear brake rotors and pads. The bed has some tie-down straps and another brushy thing.
Firebird: Whatever the gf has in it. I think my Autotap cable is hiding there too.
Freestyle: Some cardboard boxes laid flat, a $12k industrial inkjet printer for Kroger on Monday, my tool case, yet another brushy thing, my belt.