Heard a lot of this growing up like Seeger, Peter Paul and Mary, Joan Baez, but also Canadians like Lightfoot and Stan Rogers. Lately I've enjoyed some of the IWWs compilations of workers' songs, Utah Philips etc. Phil Ochs is up there too.
My mother's from an assimilated Mennonite background and it was one of the non-Christian genres that was permissible to her parents, because of the pacifist and civil rights sentiments in a lot of that music at the time. Also it lacked the sex and drugs themes which rock had. "I Aint Marching Anymore" and "Where have all the flowers gone?" I remember hearing quite often.