Only one? Not fair! (My friend has--I think--9 books of Milton in his head now. Sometimes makes it a bit difficult for anything else to lodge there.)

My first thought was Kilkelly, for the story of going away and never coming home. THen Harriet Tubman with its highly political 3rd verse. My youngest asks for it often. NOT The Cat Came Back, I'll let HIM learn that one. Rabbitrunning took my wedding song, and that bit of history. But I think it might be Swing Low, because my Dad and I used to sing it in the car, and I sang it at his funeral. Hope in a difficult situation.