I want to go to the site of the CP-1 reactor. Not much left but a plaque, but that's where the modern age really began. Apparently you can buy some graphite from the CP-1 as a paperweight, but I'm not sure how legit it is. They say you can buy trinitite too, but the market has a lot of fakes.
For a time, Argonne National Laboratory was raffling off lucite-encased blocks of CP-1 graphite at conferences. They probably have a stockroom somewhere of the stuff to give to VIPs, etc.