To dream of a shovel represents your search for wisdom, comprehension, and your true self. You are partaking on a journey of self-discovery. It may also mean that you are putting too much effort into the pursuit of solution.
To dream that you are digging suggests that you are expending too much effort. You may be attempting to get to the bottom of a situation that has caused you grief. You could also be concerned with self-discovery or your inner persona.
To dream that you dig a hole and discover something shiny suggests that there will be good luck coming your way.
To dream that you dig a hole and fill it with water signifies that regardless of your effort, you cannot get things to turn out the way you want. You should understand the concept of compromise.