Dreaming of the letter M means you are keeping hush about certain things. The constant act of upholding secrecy may lead to paranoia. Start reviewing these secrets, and determine whether it is pure nonsense, then let it go to free your mind for more constructive things.
Also, the letter M represents your mother. You may not have spoken to her in a while, now is time to pick up the phone and reconnect because she’s probably thinking of you too at the same moment.