I need help !!

[NA N.]

So here is the guy knocking on my door while i was at work, my son opened it he dramatically asked if his parents were at home. FIY (my son is 18 years old.) My backyard is flat except in the farther side of it their is a hill that almost other subdivision across it can see it. in that hill since some of it is my property i throw my wood stuff in there with some motor thingy and other stuff , its definitely not a trash. and this guy comes in tells my son that if we don't clean that area he would call the (DOD) something something organization and police on me. i wish i was home to talk to him that that little area is my property and i can throw anything i want to as long as it does not bothers my neighbors. i need help  understand this better......... am i right ? does he has the right to call the police or some other organization on my property ? please help!