Peter Yarrow — part of the musical group “Peter, Paul and Mary” — campaigned in Iowa this weekend on behalf of Massachusetts Senator John Kerry. Yarrow’s wrote a song for Kerry, a present for Kerry’s recent 60th birthday, and he performed it. He says he’s an organizer and believes that music and unite us and unite our hearts. He says he believes Kerry’s campaign can unite us all. Yarrow sang “America My Own” during the event. Yarrow and Kerry have been friends since 1971 and he is the godfather of one of Kerry’s children. Peter, Paul and Mary’s biggest hit: “Puff, the Magic Dragon.” He closed the Kerry event by singing another hit, “If I Had a Hammer.”