What mythical creature can read minds?

The "creature" you are talking about is not mythical. Angels can travel through your dreams and always know what you are thinking. Castiel is a fallen angel who is the "angel of thursday." Angels send you dreams sometimes that can be interpreted through prophecys. Little flicks of your life that has not happened yet is commonly referred to as E.S.P., but it is actually bits of prophecy for tomorrow sent by an angel in Heaven that is close to you, or maybe even your guardian.