There may or may not be local laws covering this situation. What you should do now is to consult with a local real estate attorney. In lieu of that, you can go to your town hall and ask the zoning enforcement officer about the "nuisance" laws regarding such a situation as yours. Typically, there are ordinances covering foul odors, excessive noise and (as in your case) unsightly trash on neighboring properties.However, before taking legal action, try to talk to your neighbot first (if you have not already done so). If that doesn't resolve the problem, then write a polite but firm letter. If that fails then it will be time to pursue your legal remedy, if any.  Just be aware that nuisance laws are different for rural versus suburban or urban settings.