I've got a song

I've got a song,
It's about so high,
It's about this big around,
It's got a wonderful sound,
But I can't sing it.

I've got a song,
It's a shade of green,
Embroidered all over with birds,
But I don't know the words,
So I can't sing it.

Some day I'll get on a mountaintop
And open up my mouth,
And this great big song
Will come rolling out
And echo North and South.

I've got a song,
It's three miles long,
It's bitter and strong and gay,
And I'll sing it some day,
And I'll sing it some day.