So, I was down at Jack London Square earlier. Bought a bottle of water, sat down on a park bench, and set my jacket beside me. Guy on the bench across the way asked me a question and I walked over to talk to him, leaving my jacket on the bench.
The conversation lasted a little longer than I'd anticipated (otherwise I'd have brought my jacket with me), and when we were finished, I turned around to see a (probably homeless, judging by his state of cleanliness) dude walking off with my jacket.
I ran after him and called out, "Hey! That's my stuff!"
He very apologetically handed it over, and I walked off while he went rummaging through the nearby trashcans.
He caught up with me a block later, on a bike with a little trailer on the back, and apologized again. He wanted me to know that he was not a thief. "I find stuff," he said, gesturing at the trailer. He thought the jacket had been left behind.
I shook hands with him and told him there were no hard feelings, which is not entirely true. I am in equal measure pissed off at myself for letting my stuff so casually out of my sight in an environment where I should know better, and pissed off at him for having such a low standard for what constitutes "found" property. But there seemed to be nowhere else to take the interaction unless I wanted to get the cops involved, which I did not.