The Amboy Dukes' second single was "Journey to the Center of the Mind", which featured lyrics written by the Dukes' second guitarist Steve Farmer from the album of the same title whose cover features a diverse array of drug paraphernalia. Nugent, an ardent anti-drug campaigner, has always claimed that he had no idea that this song was about drug use. "The Amboy Dukes" (1967), "Journey to the Center of the Mind" (1968), "Migration" and "Rusty Day" (1969)—all recorded on the Mainstream label—sold moderately well. On April 5, 1968, the day after the assassination of Martin Luther King Jr., Nugent joined other musicians in a tribute to King by having a folk, rock and blues jam session. Joni Mitchell played first, followed by Buddy Guy, Cactus, and Jimi Hendrix. Other musicians who participated were BB King and Al Kooper.