Hang on to your hats everyone – mystery solved! The mystery woman is “C” of ABCDMCachers (Carrie), and yes it is her hat. She didn’t realize that it was missing until I noticed this forum.
We found an overview photo of the picnic and we see exactly where she left it. See if you can find it (hint: ybbx haqre gur cvpavp gnoyr).

OK, now that the mystery is solved, what should be done with the hat? Carrie has no strong attachement to the hat so she’s fine with using it as a mascot, or using it as a TB (maybe its goal could be to be signed by everyone who attended the picnic), or whatever else you can think of. Or just feel free to put our name on it and drop it in a cache somewhere between where you are and Brookfield, and we’ll pick it up.
Thanks for the amusing (and somewhat odd) posts! Doug (D of ABCDMCachers)