Grammy-winners Peter Yarrow and Noel Paul Stookey carry on the proud tradition of the 1960s iconic folk-singing trio Peter, Paul & Mary. Peter and Paul continue to perform as a duo, singing many of the group's classic hits, including "If I Had a Hammer," "Blowin' in the Wind," "Puff (The Magic Dragon)," "I Dig Rock & Roll Music," and "Leaving on a Jet Plane” at Boardinghouse Park, 40 French St., Lowell. Tickets $54 in advance, $60 day of show.