My most famous (and recent) "loss" was my 3 1/2 x 18 inch ruler. I'd taken it to a sewing day and couldn't find it when I came home. Emailed the organizer who gave me the janitor's contact info, emailed him and the ladies who run the comfort quilt part of our guild (where the janitor was to put the ruler if he found it).
Long story short, no one had found it, I couldn't find it, so I replaced it, but I couldn't find the same brand with the same lines anymore which saddened me. Then, about a week after buying the replacement I was lifting my machine to put in its' tote prior to going to another sewing day, and I saw the corner of the ruler sticking out from the edge of my sewing machine at the back side.. I must have somehow set the ruler under my machine in the tote when I packed up the previous time and it stuck to the bottom and the edge that stuck out wasn't visible unless you were looking at the back....I'm glad to have it back!