Fortunately for you, John, someone did not have enough time (or enough interest) to find a buyer. We observed similar things in the apartment complex where my wife’s parents lived, near a state university, at the end of every semester. Students who were moving on would discard any piece of furniture too hard to move themselves; Deb & I guessed these were family pieces donated to the students, who had no use for them after graduation. “Recyclers” in pickups would cruise the dumpsters looking for finds. Sometimes furniture would appear at a dumpster, vanish, then appear again the next day (scavenger’s remorse?).
I hope some people benefited from those castoffs as you did!