“The feeling was just pals hanging out,” the photographer Henry Diltz says of the February 1969 shoot that yielded the cover of Crosby, Stills & Nash, the first album by one of the world’s first supergroups. “Those were my friends—the people I hung out with and smoked grass with.” Thanks to Diltz’s indelible photograph—three guys on a ratty couch on the porch of a little white clapboard house—that record became forever known as the “Couch Album.”

It also fixed David Crosby, Stephen Stills, and Graham Nash in the public imagination as a trio of friendly neighborhood rock gods (from the Byrds, Buffalo Springfield, and the Hollies, respectively) who had a supernatural ability to bring front-porch intimacy to stadiums and arenas and festivals—including Woodstock, where they played their second-ever live show, joined by Stills’s old Buffalo Springfield bandmate Neil Young, in front of, oh, about 400,000 people. “We were scared shitless,” Stills said of the occasion.