An old folk song. You can also find many other versions including those from Joan Baez, Simon and Garfunkel and Bob Dylan.
Grateful Dead: Cameron Indoor Stadium, Duke University 4/12/1978
Grateful Dead: Las Vegas 6/26/1994
Ratdog, Cleveland, February 2008. You can skip ahead to about 1:48 to miss the switching of the bass guitars.
Donna Jean Godchaux Band. Date ??. No hurry on this one.
The Dead, DC, April 2009. I don’t particularly care for the video but the recording is pretty good. I do like Phil Lesh singing this song.
