I love that you are trying to find out for your Grandma. The song is from the 1949 film 'Tulsa' and is sung by actor Chill Wills. It was used in a lot of the radio adverts, and if she went to school in the area of Tulsa, the school may have been sent the sheet music and lyrics.
The full movie is on YouTube for free. She can watch the song being sung here https://youtu.be/hwtOz4px9Kk at 13 mins 50 seconds.
I hope she (and you) enjoy it.
Best wishes, from a film librarian in Englandmore »