Do police officers have to show you the evidence when the arresting you

A friend and I were pulled over taking out of the vehicle on the side of the road for two hours while they searched her vehicle. At the end they came to us put cuffs on both of us told us we were charged with paraphernalia , We had no idea what they were talking about. They said there was a white powder on both of our seats. They would not test it in front of us they would not even show it to us. It was freaking french fries salt. There was no drugs in that vehicle and we were both arrested for nothing.