Man, where does a guy really start? So many of the ones already given have been stuck under my skin for years, too.

Someone beat me to "I gave her my heart, but she wanted my soul"

"He's a pilgrim, and a preacher, and a problem when he's stoned"
                Kris, "The Pilgrim, Chapter 33.

"I have seen the David; I've seen the Mona Lisa, too; and I have heard Doc Watson play Columbus Stockade Blues"
                Guy Clark, "Dublin Blues".

"You come home straight, and you come home curly; sometimes you don't come home at all"
               John Prine, "The Speed of the Sound of Loneliness"

"Yesterday's dead, and tomorrow is blind, and I live one day at a time"         
               Willy Nelson, "One Day at a Time".