"Harold and Maude", Hal Ashby's 1971 black comedy starring Bud Court and Ruth Gordon with a soundtrack by Cat Stevens. I saw it once on TV about 40 years ago. I'm not aware of it being shown again since, so I think that qualifies as "forgotten".
Also "Little Big Man" from 1970 starring Dustin Hoffman.
Harold and Maude. Forgotten? Really? No dear.