A member of The Dream include any people who live between dimensions and subsist on the essence of dreams of others. The name of their parallel world is simply The Plane of Dreams.... More, these beautiful creatures resemble trees. They have control over plant-life, and – like all members of the Dream – feed off human dreams in sleep. (Don’t worry. That part benefits us.) Closely related to both A member of The Dream, these beautiful creatures resemble water spirits. They have control over water, and – like all members of the Dream – feed off human dreams in... More and Sylphs.
What makes them stand out is they’re slightly more awake and aware than most people of The Dream. You could actually have a conversation with one, and that’s saying a lot.
Note: this applies to the current surviving Dryads. There used to be a portion of their race that fell into the Guardians category, but they were all destroyed in the First War.