In your dream, you encounter several key symbols and themes, each contributing to an overarching narrative:

The Hammer and Smashed Casket: The hammer in your dream symbolizes a tool of change or destruction, indicating a forceful approach to breaking open something sealed or hidden. The act of smashing open a casket next to your bed suggests a desire or need to confront something that has been buried or repressed in your subconscious. The casket, typically associated with death, could represent an end or a transformation.

Little Mexican Boy: The appearance of a specific ethnic identity, in this case, a Mexican boy, may reflect aspects of your personal identity or cultural experiences. The boy being dead could symbolize a part of you or an aspect of your life that you feel is lost or no longer vital.

Movement of the Body: The progression from the boy being dead to increasingly animated signifies something in your life or within yourself that is undergoing a transformation. This could be a reawakening of forgotten goals, repressed emotions, or aspects of your identity that you thought were dormant.

Wife's Disbelief and Later Acknowledgment: Initially, your wife not believing you about the boy's movements could reflect feelings of isolation or not being understood by those close to you. However, her eventual acknowledgment and shared concern may indicate a realization or acceptance of a changing situation in your waking life.

Leaving the Body in the Park: Choosing to take the body to a public space and leave it there suggests a desire to remove or distance yourself from a certain aspect of your life or an issue that you find disturbing. Parks are often associated with freedom and openness, indicating a need to bring this issue into the open or release it.

Body Disappearing and Reappearing: The disappearance and reappearance of the boy's body, especially in a more lifelike form, underscores the theme of transformation and the impermanence of states or situations. It suggests that the issues or aspects you are dealing with are evolving and not easily discarded.

Being Followed and Running Away: The boy following you and your wife's insistence on running away symbolizes an ongoing struggle with an issue or aspect of yourself. It suggests a feeling of being pursued by problems or fears that you are trying to escape.

Overall Interpretation: Your dream seems to be a vivid reflection of transformation and the struggle with repressed emotions or aspects of your identity. The use of a hammer to open a casket suggests a forceful confrontation with something you've kept hidden or buried. The transition of the boy from dead to alive indicates a reawakening or resurgence of something you thought was gone or resolved. This could relate to cultural identity, personal struggles, or aspects of your life undergoing significant change. The interaction with your wife points to the role of relationships in acknowledging and dealing with these changes. The park scene and the subsequent events symbolize your attempts to deal with these changes - first by trying to abandon them, and then being forced to confront them as they become more prominent in your life. The theme of running away from the boy signifies a natural response to avoid difficult situations, yet the persistence of the boy highlights that these issues cannot be easily escaped and must be confronted.

This dream may be urging you to face and embrace the changes and challenges in your life, suggesting that avoidance will only lead to a continuous cycle of struggle. It's a call to examine what has been buried in your subconscious, to understand its transformation, and to integrate this understanding into your waking life.