Sounds like my experience.
I bought a house from an editor of a prominent daily newspaper, but there was one strange event in our first survey of the grounds: the realtor virtually body blocked me from going around to the back of the outdoor tool/garden shed.
I thought it was odd at the time, but didn't realize until after closing why: they guy had piles and piles of little lumber pieces, tin cans, gardening junk, half-full mulch and fertilizer bags, etc, all hidden in decaying heaps behind the shed. I'm talking 3 to 5 foot high piles.
I filled up an entire mid-sized dumpster with the refuse this guy left in the yard.
It was a the "Harry Homeowner" version of hoarding.
His version of "getting it all out" involved taking it out of the garage and dumping it in the driveway. I am talking about a pile that filled the entire two-car turnout and was too tall for my 6'6" husband to see over. Broken chairs, bed frames, half-empty dried up paint cans, old bedspreads, broken window frames . . . you name it!
We found a good solution though. My husband called the garbage collection service that this fellow had been using (apparently he didn't use them much!) and proposed that we would keep them on if they could send a truck and a couple of men to clear out the driveway. They agreed, and it turned out to be a good deal for them - we're still here and still using them after 12 years. Occasionally they spill a little garbage or one of the men leaves a cigarette butt in the driveway, but they do a good job overall and we can't complain.
You should have taken it and dumped it all in the realtor's front yard. They make me SICK!