At the turn of the '60s, a quartet of New Jersey teenagers became one of the brightest successes in girl-group pop. The Shirelles mingled pining vocals with string-swept sweetness on their gorgeous breakthrough ballad, “Will You Love Me Tomorrow,” while “Soldier Boy” and “Baby It's You” offer just as much aching tenderness. Yet the group showed off a more seasoned, swaggering side on “Mama Said,” an empowering ode to sticking it out through life's hardships. Balancing winsome harmonies with wistful romance, they created woozy, youthful valentines that usually lasted less than three minutes—but have lingered for decades since.