Dreams involving graveyards often symbolize reflection on the past or dealing with feelings of loss. Walking with friends suggests a sense of camaraderie and support in your life. The cobblestone bridge can represent a transition or connection between different aspects of your life, possibly between the past and the present.

Dropping the penny into the water may indicate a desire to let go of something or make a wish about your future. Water often symbolizes emotions, and retrieving the penny could signify a need to reclaim something valuable from your past, whether it's a memory, an experience, or a part of yourself.

Your friends leaving the graveyard while you stay behind might suggest that you feel a sense of isolation or that you are currently in a phase of introspection that others around you may not understand or share.

Overall, this dream could be prompting you to reflect on your past and consider what you want to carry with you into the future, as well as highlighting the importance of friendship during times of self-discovery. It may be beneficial to take some time to think about what the penny represents for you and how it relates to your current life situation.