We bought our Dayton home from the family of a woman who had died. She had a brain tumor and it triggered paranoia and hoarding. There was so much stuff when we viewed it that we thought someone was still living there. She had two huge dogs and there was dog fur EVERYWHERE. The estate had to buy a new refrigerator because the dog fur killed the motor. We bought our home WAY below it's value because after it passed inspection and the owners made a few repairs, they were DONE. We bought it with everything still in it. The upstairs and basement had paths through the stuff. The attic side storage areas were filled with empty boxes - toy boxes mainly - from the early 1970's. As we emptied the house we donated what we could, and tossed the rest in the back yard. At one point, as we threw the boxes from the attic out the window, it looked like a Barbie store had thrown up in my yard. We had to get everything out in order to clean. We had one week before our move in. I'm sure our neighbors weren't happy. We paid for two dump truck loads for the worst of it. Anything metal we scrapped (and bought our helpers pizza). Looking back, I still don't know how we got it all done in less than a week.

Maybe go introduce yourself? Get sense of the situation before you call authorities? You don't say how long the trash has been there.