Little Boy Blue is a Mother Goose song from Richard Scarry's Best Sing-Along Mother Goose Video Ever.
Only his feet are shown when he's sleeping under the haystack. His full body is shown when he is awake to blow his horn.
Little Boy Blue
Come blow your horn
The sheep's in the meadow
The cow's in the corn
Where is the boy who looks after the sheep?
He's under the haystack, fast asleep