we've had the usual: phone chargers (thanks, they can go in the basket in the cottage for future guests), socks, swimwear, but the sweetest one was a pink water bottle left by a little girl, and not sure why it was special ( was about $30, so not a cheapie, but still.... as a parent i might have used it as a teaching moment). Anyway they contacted us, they live down in the city, about 50kms away, but my daughter was going into town to do an Ikea run (oh, for these same guests who had broken the bed!! and hadn't mentioned it, we assumed the kids had jumped on the sides, there's no way those 2 adults were getting any "them time" haha, not with the 2 kids they had with them, anyway the beds weren't super high quality and about 7 years old so we just figured it was wear and tear) and buy new beds so she dropped the water bottle off at their house as it wasn't far from the Ikea. side note: if you need to buy a bed (2 beds actually, we replaced both) today, the only place - at least in Adelaide - is Ikea. covid/supply chain/blah blah blah.
Turns out they own a business that sells those sticky rollers that remove hair and fluff, and they sent us their deluxe model and 2 refills. And the little girl wrote a cute thank you note. How lovely!