How do trick my prof into thinking I handed in an assignment on time?

Find an old email you forwarded, and copy that little message at the top that states the To: Date: and Time: Fields. Paste it into a new email, and change those fields to reflect sending it to your professor on the proper date/time. Then, change one letter in the professor's email address.

Forward that little thing with the assignment attached and say "I'm so sorry! I found it in my outbox and realized I made a typo in your email address."

Apologize and take full responsibility. She'll be so astounded she might be impressed enough to forgive your laziness.

Yeah professors don't like it when you try to insult their intelligence by tricking them or making up excuses. Just take full responsibility and ask if there is any extra credit you can do to make up for it.

Idiot