Dreamscale

Dreamscale is used in one epic-level Dragonscale Leatherworking pattern.

Source
Dreamscale can be found by skinning the raid-level green dragons near the portals to the Emerald Dream in Ashenvale, Duskwood, Feralas, and The Hinterlands.

Dreamscale as an Ingredient
Dreamscale is used in the following recipe:

Leatherworking

 * Dreamscale Breastplate