Interesting question for sure. What I've wondered more about is what items of significant importance and value have inadvertently been tossed or thrown away. I mean everyone's mom tossed their cards growing up right?
So many of my advertising pieces were found in the craziest places and could have been easily overlooked and lost to the elements of weather (Ruth tri fold under porch in Portland Oregon) or simply the landfill (Spalding Base Ball Good sign found behind a cheap framed picture) to others found in the walls of homes that were set to be demolished.