I’m in my 40s and only heard “We Shall Overcome” last year. For at least 30 years I’d been aware of it’s existence, know of it’s importance, known the circumstances of many famous performances, known many of the lyrics from having seen them written out. However I’d never actually heard it except for a couple seconds here and there. I finally heard it performed last year.
I mentioned this at the time on some forum (can’t remember if it was SD) and many people had the same experience as I did.
I bet a lot of people know it from Casablanca, though.
I bet a lot of people have heard the Pastoral (“Call to the Cows”) and Finale (“March Of The Swiss Soldiers”) from the William Tell Overture and don’t realize they’re from the same piece.
I learned it in French in high school; I always assumed at least a few other people might have done the same.
While we’re on music people know mostly from cartoons, you could add a lot of the works of Gilbert and Sullivan. I don’t think there’s any G&S song I’ve ever heard that I didn’t hear first in some sort of parodic context.
And it wasn’t until just this year that I learned that “Turkey in the Straw” has actual lyrics of its own-- I always thought it was just a fiddle tune.
One that I’ll bet a lot of people are familiar with the melody of, but don’t know the song or its name)is one I’ve brought up several times on this Board. It’s the “old style college music” you always seem to hear when they show you the ivy-covered buildings of Oxford or Harvard. The song is Gaudeamus Igitur, and I first learned what it was by hearing a Classical Society singing it when we were all huddled inside a Roman monument. The lyrics and the music were in the back of my Latin book, but I’d never made the association:
Huh, I’ve never noticed that used on-screen, but I was familiar with it from playing it in band at graduations.
Similar, there is a current insurance company commercial that uses the old (1986) Human League song “Human”, but only used the one line “I’m only human, born to make mistakes.” The song is about a couple that both cheated on each other. (Can you get insurance for that?) I like the song, but I’m old, too. Does it still get airplay?
The Green Fields Of France, originally entitled No Man’s Land was written by Eric Bogle, a Scottish-Australian folk singer, in the 1970s. It has entered the canon of Irish folk as it is an astoundingly beautiful song but credit where it’s due. 
Eric Bogle also wrote ‘And the Band Played Waltzing Matilda’. Instead of listening to the Dubliners singing it, find a YouTube clip of Boges doing his stuff.
Oh, and keep a box of tissues by your side.
I think many people understand the cultural significance of Strange Fruit, but haven’t actually heard the song.
I can honestly say I’ve never heard those titles, although it’s possible I’d recognize the music.
Actually, going in the opposite direction, being an American and only 10 when the song first came out, for years I didn’t realize that U2’s “Sunday Bloody Sunday” was a reference to anything.
Just out of curiosity – in what sense are these songs companions?
Sorry if this is a highjack from the original topic, but people are going on as if The Band Played Waltzing Matilda as the only song out there. 'Tis a great, poignant song. However, to cap off the sorrows, listen to Barrett’s Privateers: Stan Rogers - Barrett's Privateers - YouTube
Elgar’s Pomp and Circumstance is a good example. People think they know it from hearing it at graduation ceremonies, but the part they know is just one section of the first of six marches.
Tchaikovsky’s 1812 Overture is another one … the part that everyone knows is the very last bit, with the cannons. There’s a LOT of music before that.
In grade school when someone had done something wrong and was going to catch heck for it we had a little line of “Dum-dum-de-dums” we’d intone.
It wasn’t until I started piano lessons that I found out the song was Chopin’s Funeral March.
Long before graduation I only knew it as Macho Man Randy Savage’s intro music.
“Call to the Cows”? So Spike Jones’ rendition with cowbells is appropriate! Spike Jones William Tell Overture - YouTube
Many people, at least of my generation, only knew “The Colonel Bogey March” as "that tune they whistle in The Bridge On The River Kwai - if even that.