As usual, the pet images used below are taken from warcraftpets.com as is the information I use. The pet name will link to the pets detailed page at warcraftpets.com.
BunniesSpring Rabbit. The Spring Rabbit is a vendor-bought pet available during the holiday for 100 Nobelgarden Chocolate's.
LambsBlack Lamb and the Elwynn Lamb which costs 40 Champion's Seal. Again, same model, slightly different skins but the same set of abilities. I only have the Black Lamb in my collections and in all honesty I prefer it to the white Elwynn Lamb.
ChicksImperial Eagle Chick and the Jade Crane Chick. Not what I was thinking of. Then, I remembered about Egbert - your typical half-hatched baby chick. Egbert is available as a reward during Children's Week (which will take place at the end of this month).