A dream book is a collection of narratives that have dream-like qualities, which means that they mix rational and irrational elements sometimes presenting improbable events as ordinary or based on fact. To say these are dreams is to sanction this departure from verisimilitude, to allow for surprise and illogic which are the stuff of dreams. So the title alone suggests that the collection is a series of dream-like scenarios or scenes somehow connected to an American period of racial injustice.