By Rob Brunner
Updated June 18, 1999 at 04:00 AM EDT

In the late ’60s, Brazil was full of such celebrated arty musical eccentrics as Caetano Veloso, Tom Ze, and Gilberto Gil. Add Os Mutantes to that list. Formed in 1966, the underappreciated trio played highly inventive psych- bossa nova, ranging from delicate balladry (a lovely cover of Veloso’s ”Baby”) to cheerful weirdness (just about everything else). Also check out their first three albums, recently reissued on the Omplatten label. The Best of Os Mutantes: A-