Not on my commute, but on single track, I found a woman's wallet with a large amount of cash in it. I had just passed a couple of female hikers about a mile back and had not seen anyone else. So I turned around and chased them down. When I caught up to them, the owner was looking in her pack, which she forgot to zip and sort of freaking out due to her wallet missing. I rode up and said, "Are you (whatever her name was on her license)?" and she goes, "yes!" I handed her the wallet and she was so happy. Oddly enough, I saw her and her friend hiking a few days later and wouldn't you know it, her pack was unzipped again. I stopped and said, "Hey, do you remember me?" and she said yes. I pointed out her unzipped pack and we all had a good laugh. Luckily this time the wallet was still there. Hopefully she learned her lesson after the second time.