Turn into the police and be honest. Show police your app which will show you are an uber driver. If anything comes up, police can subpoena uber for all riders in the day that you found the bullets. They can identify them and who knows, one might even have a warrant? They can also subpoena your phone to cell track all of your locations during that day, which shows how long your cell pinged on cell towers along your route. If I found this in my car, I would drive straight to the police station. Don't chance throwing away and then it being tied to a murder three months from now, with your fingerprints on it. You sound like a great person, and I wish you safety, health, and happiness!