When the seeds are ripe, and I do mean ripe, shiny, hard black like peas, otherwise it's a nono, gather them and roast them (dry cast iron frying pan) until they are cooked and crack. Store them like this and when you want to use them hit them with something like a rolling pin and then re-roast them until dark brown/ black. Use them like coffee.
There has been a discussion about acorns for coffee, usually they need leached of tannin, but around here many of the acorns are very mild, almost edible just as they fall off the trees, they don't need leached, I don't know if this is true of our Flag Iris too, I've lived in this small area all my life and it's quite a surprise to realise that folks don't know that even within the same species plants have a lot of variation. Our Bour trees, (Elders) are all different, some are better taken as flourish, some left for wine and some are fit to eat just as is.
I tried the Rosebay WIllowherb again after reading on the forum how it's best prepared...........the stuff that grows round here is still vile
Know your area, learn the taste and smell of the ones you use is the best advice I could offer.
As for toxicity, well I reach my half century shortly, Flag Iris coffee is an occasional drink, like dandelion or acorn, and I've never noticed any ill effects. There are huge differences in the properties of the fresh or dried roots though, maybe the seeds are similarly affected ?
cheers,
Toddy
