Spiritually mud represents the very basic materials of earth and water from which we are all formed, and thus its appearance in dreams indicates the need to go ‘back to basics’.
Psychological / Emotional Perspective:
Mud represents the fundamental substance of life, which, handled properly, has a tremendous potential for growth but, handled badly, can be dangerous. Many cultures believe mankind was fashioned from clay mud to give him structure. In dreams, if the mud is too dry we have suppressed emotion, if too wet, like marshland, we cannot develop a proper way of working.
Everyday Material Aspects:
Mud in a dream suggests that we are feeling bogged down, perhaps by not having sorted out practicality and emotion (earth and water). Mud can also represent past experiences or our perception of them, which has the ability to hold us back.
You might also like to consult the entries for Earth / Earthquake, Marsh and Water.