LETTUCE is (a) the prime ingredient in a salad, (b) a slang for cash, (c) a green herb that can be smoked, (d) a genre-busting six-member funk/jazz/soul/jam/psychedelic/hip-hop/avant-garde/experimental collective formed in 1992 by four alumni of the prestigious Berklee College Of Music, or (e) all of the above. If you answered “e,” then you’re on to the ever-changing musical palette and all-inclusive goals of LETTUCE’s sixth studio album, Elevate, and its ongoing re-interpretation of the band’s name as “Let Us.” In…