We’re hopping in the time machine and setting the controls for April 1968, to take a deep dive on Simon & Garfunkel’s “Mrs. Robinson,” the weird and unsettling world of Tiny Tim, and the format-bending sound of San Francisco’s Moby Grape—as well as the ultra-dedicated unofficial archivists like DustyGrooves69 and Vintage Recordings, who make sure we can access it.