Probably a reference to Mother McCree's, but this from a ca. late 1970 - early 1971 interview with Jerry by one Frank Fedele, who asks him about what he was doing before GD. Jerry says "We had a jug band together, me and Bob Weir and Pigpen and we worked once or twice a year. I mean, nobody fucking hires jug bands."
Seems obvious, if a bit hyperbolic, but I thought it was worth pointing out that there may not be that much MMUJC stuff out there in part because they may not have performed that much.
-->Fedele, Frank. 1971. Fuck No, We’re Just Musicians: An Interview With Jerry Garcia. Organ 1, 8 (June): 14-15, 22 (quote from p. 14).