They also left some stuff in the garage, including something that's basically a bulky endtable cabinet, but will work fine for storage. I decided to wipe the dust off it yesterday and store some tools in it, and after clearing out a few loose screws and nails, I found these stuck to the shelf in the very back:
Note the small size of these ziploc bags. In my mind, there are only a few things small (and yet valuable) enough to need protecting in a bag; collectible coins or stamps would be the "benefit of the doubt" assessment. But you know, unless someone was a real bad-ass philatelist, it seems unlikely they'd keep their walking around stamps in bags imprinted with devil heads or spades. The fact that they were stuck on the shelf is also damning- I'd think you'd store your stamps somewhere less prone to damage.
My guess is that they cleaned this cabinet out when they moved out, but didn't feel in the back and notice the bags stuck there. For whatever reason they were saving these (believe me, they looked too used to repackage anything saleable in), they must have forgotten about them when they cleaned up and didn't miss them.
Makes me wonder what other garage treasures await my discovery...