Do you have squirrels in your neighborhood?
I have a grunch of them around the house in the woods. One of the little boogers stashed a black walnut inside the alloy wheel of my Honda Element.
Ting a dee ting ting we went out of the neighborhood.
Pulled over and found the black walnut between the wheel and rattling against the brake disk. Removed the walnut, no more noise.
I guess Mr Squirrel is still looking for that thing...
2006 Sunseeker 3100SS/LTD
2008 Smart Passion Cabriolet TOAD
1986 Honda Helix (Original owner)