Interesting...if we can agree upon something fairly inconspicuous. Perhaps a feather charm suitable for either a mans or womans bracelet? It would be fascinating to see how long it took us to run into someone else sporting one. I'd be betting on an encounter at an airport or sporting event....
Yes, I think it would definitely have to be something subtle, yet recognizable. Any of those things would probably function well. I would suggest simply the letters TMF with an image of a feather behind it, whether it be on a t-shirt, baseball cap, ring, or necklace, etc.