WoWDB

This hat can either be a rare drop from Brightly Colored Eggs collected during Noblegarden, or can be purchased with 50 Noblegarden Chocolates found within the eggs.  You can also purchase a Pink Spring Circlet and a Black Spring Circlet variation.

At this time, the hat cannot be used for transmog on real items since it is not technically classified as an armor type (you can, however, transmog it to other silly/fun/costume hats).