This isn't quite the same thing as a "work culture canary", but it offered an interesting (to me, at least) perspective on coworkers.
On two occasions, once in a large media office in the UK for a year and the second time in another large media office in Australia for two-and-a-half years, I maintained a huge stash of chocolate bars in the drawers at my workstation. In the UK, I'd leave the drawer open to display the wares; Twix, Milky Way, Flake, Rolos etc, and also bars of slightly better chocolate - Toblerone, Green & Black's etc.
People would drop by for a chat, take what they wanted and go on their way. Quite a few would cut the chat, grab a bar and leave with a grin or a thumbs-up or similar. I liked it that they cut to the chase; didn't feel awkward about taking what was freely offered without feeling obliged, for weird social/politeness reasons, to make smalltalk.
At the time, we'd had a bunch of teenagers working to sort out, manually, a huge mess with a football (i.e. soccer) score/results feed, which was spewing all sorts of rogue data. The teenagers were all keen followers of the sport and could spot errors reliably. One was my nephew, a law student, one was a friend's son, an English Lit student, and the other two were sons of a colleague, one an economics student and his brother in his final year of school. This crew were stationed all around my workstation. They were really observant.
It surprised me to find out that some colleagues would avail themselves of the chocolate drawer only when I wasn't at my desk (too many meetings, so for at least an hour during the working day). Others, I was told, whose regular choices would be Twix, Rolos or similar, would, if I were absent, hit the better stuff instead. My young observers had great fun with this people-watching stuff, and it amused me greatly.
In Australia, I kept drawers stocked with standard bags of fun-size Mars, Twix, Milky Way, Flake etc, and higher-quality bars from Haigh's and Koko Black. Every day I'd fill bowls with these and leave them on a shelf in front of my desk. Although I lacked my teen crew, I found willing observers among the devs in our corner of the office - we were working on a newsroom system and doing so in the newsroom itself, so lots of journalists and ad people were our neighbours; which was a similar mix to that in the UK.
Similar patterns emerged. Some people took chocolates only when I wasn't present, and others changed their preferences based on my presence/absence.
It'd never pass muster as a proper experiment, but my biggest take-home was that "my sort of person" was happy to grab and run without chitchat, always took whatever they fancied, and never altered their habits depending on whether or not I was around. Also, and this was the same in the UK and in Australia, the "grab-grin-and-run" folks were the only ones who would, every now and then, add a pile of chocolate themselves.
Another takeout, again, it's nothing but anecdotal, was that advertising people took the free stuff only when I wasn't around, in the UK and in Australia.
Anyhow, chocolate is quite cheap and my supplies probably cost £20 to £30 a week at the time (say 10 or 12 years ago). But it's fun seeing how people react to something as trivial as free chocolate, and how it provides behavioural/social insights.