I thought I'd refresh this thread to see if anyone has more to add -- perhaps songs written since the thread was first posted.

Some that seemed to me to be relevant to the category (in addition to The Midnight Choir and Hard Times Come Again No More and Nobody Knows You ...) are

Trudy -David Maloney

There But For Fortune - Phil Ochs

Railroad Lady

Will There Be any Boxcars In Heaven - Jimmie Rodgers

Wabash Cannonball

Waltzing Matilda

Pretty Papers -- Willie Nelson

Here Comes That Rainbow Again -- Kris Kristofferson