My family used to work at our local library and art gallery when I was a kid. Every year, the library would take books that were pretty beaten up and throw them in the dump (they have a penny sale now). I found some massive 4" thick 13x17"-ish tome that looked like it was a couple hundred years old. Turns out it was 115 and the book was some enormous volume of Shakspere. Not only did it have all his plays, but it was also filled with gorgeous lithographs, like this one right here:



That's one of my favourite pieces of art that I still have today and it came out of a pile in a landfill.