At first, I grew ornamental onions in as much sun as possible. That is where they grow the best, but I have found that they will bloom quite nicely in a dappled shady spot as well. They look quite natural in a woodland setting. They will self-sow and are very winter hardy.
Double columbine which also does well in dappled shade. It is on a bit of a slope so the soil drains well. They don't like to dry out so they do well with other low growing plants nearby to shade the soil.
The ferns are happy with all the rain we've been having - very Rousseau-esque.