Can my license plate number be tracked down for free by average people?

I was in a parking lot waiting for a man to perform backups to take place. I saw the type of backup, so a backup to give him some space but I think a car was just standing behind me and hit the bumper on perhaps a mile an hour. I took my car and parked about 15 spaces down so I could talk to people . I went to his car (which took the place that I would have , first) and had already got out of it and went into the store. My car had no damage and theirs seemed fine, so .. I went to the store and tried to look for them because I felt bad and the lady seemed super annoyed when I played . can find my license plate number and charge me ? im scared and do not know what to do because I've tried looking for them, but stopped going to the store before I could talk to them. I took down his license plate number just in case ..... help please !