A book or possibly short story about 3 elves and a hole in the wall that speaks to them.

This story was read to the class by my third grade teacher at Hubbell School in Des Moines, IA, in 1949.  I remember that we were entranced by it and insisted on making it into a drama.  For our play the “elves” dressed in red long johns and the boy (Kenneth Brown) who devised the “hole” was cast in that role.  I would be grateful if someone could direct me to it because I don’t remember the story and would like to see whether, as an adult,  I can fathom what it was that charmed us so.