Experiment with
Malva silvestris toned cyanotype. I was actually doing some research on edible flowers, and found that Common mallow is both edible and can be used as a dye, but requires a mordant, and iron was mentioned, so I figured the iron in cyanotypes might work.
Malva silvestris is a really common turf weed here in NZ, so it was easy to collect a good number of flowers walking the dog. I soaked them in isopropyl alcohol diluted with water, but I've since read that people usually boil them for dye. (and dried flowers can be purchased online if you can't find them locally).
I did a carbonate bleach before toning. (I make my own carbonate from bicarbonate which is cheaper. It's available in bulk as a pH buffer for pools, but the reason it's used as baking soda is on heating, it releases carbon dioxide and becomes sodium carbonate, so all you've got to do is boil it for a bit to increase the pH.)
The blue-grey tone is interesting, and different from anything I've ever achieved with tannins.
Apparently the seeds can also be used as a dye, and produce a different colour, so my next experiment will be to collect a decent number of them and see what result they produce.