WoWDB

The Spring Rabbit's Foot that teaches this pet can either be purchased with 100 Noblegarden Chocolates, or can be found as a rare drop from the Brightly Colored Eggs.  The eggs are are found during Noblegarden around each race's second town (first proper town after starting area):  Azure Watch, Bloodhoof Village, Brill, Dolanaar, Fairbreeze Village, Goldshire, Kharanos, and Razor Hill.

If you encounter someone else with a Spring Rabbit summoned, they will get together and make some baby bunnies.