White Christmas

In 1939 Isreal Baline composed a Christmas song, but he thought so little of it that he never showed it to anyone. He just tossed it into a trunk and didn't see fit to retrieve it until he needed it ten years later for a Bing Crosby-Fred Astaire movie, Holiday Inn.
Bing Crosby was a staunch Catholic, and at first he refused to sing the song because he felt it tended to commercialize Christmas. He finally agreed, took eighteen minutes to make the recording, and then the "throw away" song became an all-time hit.

Crosby's version had sold over 40 million copies. All together, this song had appeared in 750 versions, selling 6 million copies of sheet music and 90,000,000 recordings in the United States and Canada alone.
You might not recognize the song from the movie Holiday Inn, or from the composer, later known as Irving Berlin.

But you're bound to know it, because it's on everyone's list of Christmas favorites- "I'm Dreaming of a White Christmas".