Why did Joseph’s first dream only have eleven sheaves of wheat representing his brothers but his second dream had eleven stars (representing his brothers) plus the sun and the moon (representing his parents)? Rabbi Joseph B. Soloveitchik explains that the dream of wheat reflected Joseph’s future material success. For such a thing his parents would never prostrate themselves. The dream of heavenly bodies, however, referred to Joseph’s future success in spiritual matters. For such a thing, his parents would happily acknowledge a person’s greatness. (From Yemei Zikaron, cited in the Mesoras HaRav Chumash.)