Sub-underground super-groups are not common. This is less a function of the concept's oxymoronic nature than of the fiercely independent stance of musicians toiling in this area. By definition, they are doing what they do simply because they love it. It can be quite difficult to distract them from their main focus long enough to get them to do anything else. Weeping Bong Band is a lovely exception that proves this rule.
Three members - Clark Griffin, Wednesday Knudsen and PG Six - are in the current line-up of Pigeons. One, Anthony Pasquarosa, has his own host of solo projects (Crystaline Roses, Gluebag, Burnt Envelope). And a final 'ghost member', Beverly Ketch, is half of the duo Viewer. Together, however, theirs is a rural psych engine that weeps as gently as a spring rain. This is high-provenance instrumental hippie spew from the apex of the Pioneer Valley. There's plenty of burbling psych guitar, laced with overtones that will make you conjure up visions of dark stoned nights. It is definitely music made in the day when marijuana had passed its medical-use-only status in the Commonwealth.
Which is not to infer this music is unimbued with its own mystical curing properties, especially when played at mind-bending volume. Allow yourself to be bathed in the tears of the bong. Their sweet flow will wash away all traces of your sins.