Most likely your friend who accidentally left his marijuana materail that he is allowed to have due to his medical marijuana card will not get in trouble if he came forward and spoke with law enforcement about what was found in your room. He will need to provide his medical marijuana card and an explanation why he left his marijuana bowl in your room.Law enforcement will wonder why he was in your room with the contraband. Since you have been charged with a criminal offense, I suggest that you consult with a criminal defense attorney about representation and viable defenses.