I once crossed the border from Canada with my Green Card, and was accused of not being the person that the GC was issued to. My jaw dropped because I had no way

I once crossed the border from Canada with my Green Card, and was accused of not being the person that the GC was issued to. My jaw dropped because I had no way of proving that I was who I was besides all my identification, and that's when I realized how unfettered the power of CBP was. Sometimes they are assholes and bullies for no reason. He went away for a few minutes, and then came back and let me through but I still remember it to this day.