Another is Kalmia latifolia, the mountain laurel, the state flower of Pennsylvania. According to records at the Carnegie Museum of Natural History [1], "Benjamin Smith Barton (an American botanist in the late 1700s) wrote that in the autumn and winter of the year 1790, many people died in Pennsylvania from the effects of wild honey, collected from Kalmia plants."

[1] https://carnegiemnh.org/collected-day-1959/

I know that West Virginia has entire Rhododendron forests. They are pretty awesome.

And yet we are only hearing of this now, whereas botulism risk for example is a widely known reason to avoid honey for infants.

It must end up being rare for some other reason.