The Mamas and the Papas were an American folk rock group theat were around in th emid to late 1960s, the were archetypal of 'Hippie' scene of the time and in my mind can be group with a who bunch of their piers who produced some really good music.
In America they were thought of as radicals, here in the UK they were popular with many and on the radio all the time.
The group featured 'Mama' Cass Elliott, John Phillips, Denny Doherty, and Michelle Phillips and their sound was built around complex harmonies
Some my favourite tracks include "California Dreamin", "Monday, Monday", and "Creeque Alley".
The group split in the late 1960s, each attempting a solo career but only Cass Elliott had real success, she died in the early 1970s in the UK whilst on tour, if I remember correctly