My first reading of this prompt illicited the response, “I don’t pick things up from the ground and keep them.” Then I thought, maybe I should expand my thinking a bit. “Thing” isn’t limited to physical objects. With that in mind, the coolest thing I’ve found and kept is Astrology. I found it in my teens and have kept it to this day. What makes it cool is all its nuances that reveal information embedded in observable movements.