I'd smack the hell out of that kid. I don't give a shit what parents say. I had one kid bother me like that - crazy little ADHD fucker and I knocked him down. He hit his head pretty hard on the pavement, and he hasn't bothered me since.
what you should do is go to each childs parents explain to them what their kid is doing and tell them that they need to teach their kid how to respect elders. Then the next day go up to the kids and explain to them that you dont appreciate them throwing things at you and calling you names and you would like them to stop. If they keep up the act then sit down with the parents one more time and let them know that if they arent willing to teach their kids respect then each time they throw something at you or call you a nameor what ever you will be forced to either call the police and make a complaint of harassment. good luck much love FF