OK, a few years back, Beck was rumored to have been a part of an album by the Melvins called Crybaby
, which would feature a number of special-guest collaborators. There has been some reports that Beck was on a song called "Osborne's Lament," but that some record label problems didn't allow it to be released. But in the end, it seems that Beck never actually made it to the point of working with them, so this song probably shouldn't be listed...
Beck did briefly sample the Melvins' song "Hog Leg" on "Beercan
" by the way.