Who are 'they'??

Yesterday evening when I let the dogs out I saw some men dumping half their load of brush in my yard. It was on the other side of our privacy fence between the small patch of grass and the alley. At first I didn't realize what 'they' were doing because of the fence. When I realized they were dumping unwanted branches and empty water bottles I yelled "Wait, what are you doing"?? Well they drove off but I saw that they were in a tan pick-up truck pulling a trailer full of men. So of course I did what every other woman would do; I put the kids in the mini-van and went in search of 'them'!! Thank God I didn't find 'them' because I had no idea what I would have done if I had actually found them!! I'm sure they would give me some sad luck story about how they were going to die if they didn't litter in MY yard, and I would believe them and invite them for dinner.
So this morning when I was letting the dogs out back and saw someone else putting more brush in the already huger pile I snapped!! I marched out there in my footie's and demanded to know if she knew that this was NOT a dump!! She acted as if she didn't have a clue that she was committing a crime. I explained that 'they' dumped this crap yesterday and that it was MY yard. She looked me right in the eyes and said,"THEY will be by to pick it up"!! I told her that there was no 'they' that would come by and clean it up and that I was 'they'. Then I just asked her not to put any more stuff in the huge pile. She then began to pull off the pieces that she put there. I huff off and called Matt to vent. When I went out later I saw that she had carefully removed ONLY the pieces that she put there, and all she did was drag them to the other side of the alley in my neighbor's yard. All I can think is; are you kidding me????
So please if you know who 'they' are let me know. 'They' need to come pick-up after themselves.