. . .is a painting of a yellow ribbon 'round an old oak tree. Now I may be wrong, and I’m sure many here will surely love to tell me if I am, but isn’t that song about a guy coming home from jail?
It is but the meaning has morphed into anyone who’s away.
The Straight Dope: Why do we put up yellow ribbons during wars, hostage crises, etc.?
I really, really hate that meme and that song.
Obviously not a John Ford fan. As it said in the movie, “She Wore a Yellow Ribbon” is a traditional song about absent soldiers that long pre-dates the Tony Orlando and Dawn version.
Around her hair she wore a yellow ribbon
She wore it in the springtime, in the merry month of May
And if you asked her why she wore the ribbon
She wore it for her soldier who was far, far away
Okay, admittedly the rest of the song is about how the soldier left her when she got pregnant.
Ha… I remember singing that song in some sort of grade school production…we only sang the first verse. Sweet childhood moment ruined forever! 
Growing up in upstate New York not all that long ago—say around 1983 or so—the remembrance poppy was still the Veterans Day symbol. Although, I haven’t seen it since, after moving to South Florida and Chicago.
She Wore A Yellow Ribbon is not the same song as Tie A Yellow Ribbon 'Round The Old Oak Tree. In fact, they’re sorta opposite. In one, the woman is remembering her man, in the other a man is asking his woman if he is still wanted.
Cultural memes has the cwaythietht origins. You should hear the debates about the Guy Fawkes masks in the Occupy movement!