Other things the cats have so far brought in to play with: feathers, a chunk of moss, and several pieces of pondweed. I am at a loss to see why the pondweed is so interesting; Orac seems to specialise in dragging that in, while Zen appears to be the mastermind behind the Frog Invasion.
Orac has also managed to shed her collar somewhere, and it (and its tag) have vanished into the mists of oblivion. I've now ordered a batch of spare tags and a batch of spare collars... now, if someone could sell me some slightly larger cat brains to install in these two, we'd be set.
[Edited to add: sweet_lil_sis reminds me. I'd thrown out some rather past-it cocktail sausages, legacy of the party the other week, for the local foxes. There was then an "OH GOD WHAT HAVE YOU DISEMBOWELLED AND BROUGHT IN... oh, it's half a sausage. Er, good" moment.]