Back in 2000, Mbo posted a link to this text, and the OP said this was the song he/she was seeking. The target of the link is long gone, but I was able to find it at archive.org. But since links have a tendency to go dead, it's best to post lyrics instead of linking to them.

Date: 2/3/98; 11:49:08 AM
From: "Christensen, LeonW"
Subject: 500 Miles Away From Home By Bobby Bare

500 Miles Away From Home
Recorded By Bobby Bare

(The chords shown seem to work ok, but there may be some
chord changes missing. The version by Peter, Paul and Mary
has more chord changes, as well as different lyrics).



500 Miles Away From Home
(Bare, Williams)

I'm five hundred miles away from home
Teardrops fell on mama's note,
when I read the things she wrote
She said "We miss you son, we love you, come on home"
Well I didn't have to pack, I had it all right on my back
Now I'm five hundred miles away from home

CHORUS:
Away from home, away from home
Cold and tired and all alone
Yes I'm five hundred miles away from home

(Spoken) I know this is the same road
I took when I left home
But it sure looks different now
And I guess I look different too
But time changes everything
I wonder what they'll say,
When they see their boy lookin' this way
(Sung) Oh, I wonder what they'll say when I get home

(Change to key of D - D,A7,G,Bm)

Can't remember when I ate, it's just thumb and walk and wait
And I'm still five hundred miles away from home
But if my luck had been just right, I'd be with them all tonight
But I'm still five hundred miles away from home
        
Repeat chorus (In Key of G)

Oh, I'm still five hundred miles away from home

       D7            C              G
  I'm five hundred miles away from home
  G
  Teardrops fell on mama's note,
                             Em        
  when I read the things she wrote
              D7                C                 D7
  She said "We miss you son, we love you, come on home"
         G                                             Em
  Well I didn't have to pack, I had it all right on my back
          D7            C              G
  Now I'm five hundred miles away from home
  
  Chorus:
   G
  Away from home, away from home
                          Em
  Cold and tired and all alone
           D7           C              G
  Yes I'm five hundred miles away from home

Lyrics corrected according to this Bobby Bare recording
https://www.youtube.com/watch?v=JfAmLz5Evxo