In the early '70s Jerry Garcia was starting to make solo records when the Grateful Dead weren't working. On one of those first efforts he recorded "Imagine." Before a Jerry Garcia Band show, in New York, John Lennon came by to thank him. Lennon told Jerry that his version of "Imagine" was the first time someone had covered one of John's solo tunes.
After the show they talked for a while and Jerry invited John to come back the next night to join him on stage. John said he would return the following day and do a sound check with the Garcia Band so they could work up a few tunes. Lennon never came back and Garcia thought that all the imposing Hell's Angels hanging out backstage might have "scared him off."