When I was a child, I knew monsters lived in my room - as most kids do. My monsters weren't the sharpest marbles in the bag though. You see, they couldn't see me if I was under my covers; they could only see the parts of me exposed from under the blankets.
I used to believe that Michigan had unique garbage trucks that no other state had. I was so surprised and excited to see a "Michigan" garbage truck at McChord AFB in Washington.
There are plenty more "I used to believes," but that's a good start. For a better start, my friend Angie pointed me to this website: Iusedtobelieve.com, which is filled with memories of what today's grown-ups believed as children. It's worth it just to remember a little more of what childhood was like, and how the mind makes the misunderstood magical.