Oooh. I found lots of sweetgrass.
Day before day before yesterday, on a "let's see what we can find" tour, one of my students bent down to check 'that white flower'. Which was in fact a grass. And when I checked it out, that grass was a sweetgrass, Hierochloe sp.
Which I've seen a few times, but never in this abundance. Now I know where to look for it: it grew very close to water.
Heavenly scent, has sweetgrass. Very strong scent of vanilla.
I've grown it in my garden, a few years ago, but the problem with growing grasses in your garden is, you pull them up as weeds, sooner or later.