Does anyone know where this song came from?

"I've got a song, it's about so long and about so big around; it's got a wonderful sound, but I won't sing it. I've got a song, it's a shade of green and embroidered all over with birds; but I don't know the words, so I can't sing it. [melody change for next verse] Someday I'll get on a mountaintop and open up my mouth, and this great big song'll come rolling out and echo north and south. [back to original melody] I've got a song, it's a wonderful song; it's fine and brave and gay, and I'll sing it someday, yes, I'll sing it someday." I seem to remember an old LP of children's songs, Robin ????? , that I learned it from and have since lost....