A horrible accident happened on the interstate a few years back when mattresses fell out of a pick up truck and killed several people in a car hit by them. The state of Tennessee has litter laws that outlaw open bed hauling, but folks continue to move their stuff in pick up trucks.
I once spotted a destroyed mattress on the side of the interstate, after someone hit it. The insides of the mattress was blown everywhere. I've seen chairs on the side of the interstate, and I know that these toppled out of trucks. I once saw a semi trucker run over a plastic play gym as it fell out of an open truck in front of him. No, the play gym didn’t survive.