Yard Sale!

This morning when we got up, MM and I were surprised to see a TON of cars littering the street I live on. It's a semi busy street, but this is crazy.
Reason?
Yard Sale. Apparently this is THE weekend for yard sales. I can see two of them from my apartment, alone.
I wonder, who invented this concept of selling your crap to someone else who must collect crap. Who wants other people's crap? I have visions of cave men, and women, sitting in front of their caves charging a few shiny rocks for a "barely used" pelt, or a dinosaur tooth, or something. Did Noah have a yard sale before he took off on his wonderful voyage in the ark? Maybe someone bought the Unicorns, cheap.
I have heard fable of people finding wonderful finds at yard sales. Books signed by famous authors, paintings by "real" artists ect. ect. And people buy these things, supposedly unaware that what they are buying for 25c. is worth millions of dollars. Somehow, I don't think I am going to be finding any rare antiques here on my street in Podunk. (I know I'm not, because I don't plan on going 'yardsailing' today.).
So all these cars are clogging up my street, just to go peruse other people's junk.