Glen Campbell is the male singer who sang "Sweet Dreams Baby". Roy Orbison sang the original version, entitled simply "Dream Baby" and including the words "Sweet Dream Baby". The Glen Campbell version completely changed the meaning and made nonsense of the lyrics by adding an "s" to "Dream".
Mahalia Jackson, who sang at Dr. King's request, and during his prepared speech she shouted out "tell them about the dream, Martin!" after which he began speaking off-the-cuff about his dream of equality of the races.