Answer:
You write on me and secrets I can keep. In places never seen. I spin like a top. Though stiff as a board I'm often described like a mop.
I am round. I have only one line. Circle is not my name indeed. What am I?
I lose my head in the morning and regain it back at night. What am I?
I have thirteen hearts but no body or soul.
I have wheels and flies yet I am not an aircraft.
Millions of these are crushed every morning to help people wake up.