A bit of googling ...
Spring is sprung.
The grass is riz.
I wonder where the birdies is?
The bird is on the wing.
Now isn't that absurd?
I always thought the wing was on the bird!
Spring has sprung, the buds all break
Spring has sprung and nature wakes
Spring has sprung, winter's gone
Now we sing our happy song
Tra-la, la-la, la-la, lay
Sweep the old dead leaves away
(Variously attributed to Anonymous, Spike Milligan, Ogden Nash)