Not a loss, but a near loss.
One time while riding with the sunset behind me, I noticed my own shadow. I bunny hopped over a speed bump and saw a strange shape separate from my shadow for a brief second. I rode about 50 more yards and since I couldn't figure out what it could be, decided to stop, turn around, and check it out. I'm glad I did! On the ground was my wallet, house keys, and access badge at work. I had somehow left my trunk bag side pocket unzipped and the contents came flying out when I hopped the speed bump. Fortunately, I was able to recover everything.