What type of charge is littering?

I need further clarification on my question from yesterday. I was arrested for a resisting arrest charge in Missouri and the Prosecutor felt they had a weak case so they Amended the charge to littering. I am applying for a job at the post office and I said that I was never convicted of a felony or misdemeanor crime on the resume. Was it ok to do that? I plead guilty to the amended charge of littering so I never plead guilty to resisting arrest. This happended at a municipal court. Is littering a misdemeanor or a city ordinance. I though my attorney said If they ever did a background check it would show up as a municipal ordinance violation, but I am not for sure what type of violation it was.