I learned about this story earlier today, while reading about the band called Spirit’s copyright claim to the song Stairway to Heaven. Jake Holmes had a more compelling case in 2010 (it was the same song), went to court, and settled the case in 2012.
The backstory. Holmes wrote and recorded the song, which was released on his album The Above Ground Sound of Jake Holmes in 1967. A few months later Holmes opened for the Yardbirds at a club in Greenwich Village, and Jimmy Page added the song to their set later that year. Two years later Led Zeppelin recorded their famous version of the song, which appeared on their first album, Led Zeppelin. It was not credited to Holmes.
It certainly should have been.