I'm actually still not sure these are actually them, but I cold stratified a bunch of 2013 collected Iris versicolor seeds, and these grassy things sprouted in spring. I have them in the pond and hopefully, they will grow up to be Flag Iris.
They have been tolerant of the cool temperatures and haven't minded the wet feet, so those are good signs.
Also, yesterday, I noticed one of the orange goldfish and the fat "minnow" that is definitely not the sleek slate gray and silver shiner but dark brassy black color frolicking among the roots of some uprooted peppermint and elderberry I have temporarily dipped in the shallow parts of the pond to help soak up nitrogen until I get some floating pond plants. The black one that is looking particularly FAT was floating near the surface and then the orange one swam up and sort of slapped at it sideways with its tail fins. Swimming around and repeating. I'm thinking this is spawning behavior? Though with all the shiners stalking every nook and cranny of the pond, I don't really think I will see any babies. In any case, I looked closer at the roots but didn't see anything that looked obviously like eggs.