Um, I do grow quite a few umbels including zizia aurea. I had to be bullied into trying it though, after a disastrous sowing of ordinary alexanders (smyrnium perfoliatum) which seeded swinishly everywhere. The zizia will do that also.....but nothing like to the same extent (although you will have fun yanking the roots if you decide to get rid!) The apiaceae family in general always gives a certain froth and free flowing movement in a shady wild garden. Looks rather good with the tall plain toadflax, linaria purpurea (another enthusiastic seeder).

And in Oklahoma, I couldn't hardly get them to grow (outside normal environmental range)...I suspect your experience will be more like the cooler English climate results though.
I would have liked them to naturalize.

Senna is a beautiful plant and native here, though quite rare.

I grew Golden Alexander in my butterfly garden and it is easy to grow and stays green and attractive. Beware, though, that it does get quite wide and will reseed enthusiastically. I would deadhead or plan to mulch heavily to decrease sprouts--or both.

Martha

I don't grow the senna, but do have the other two plants mentioned. They are both spring bloomers, loved by insects, and very easy to grow in part shade/part sun and relatively dry to fairly moist soil. I don't know how tall a plant you want. Senna is a much larger and taller plant, around 5 ft. I believe it also prefers a sunnier spot, and blooms in July-Aug. Check for more info on native plants on Prairie Moon's website. https://www.prairiemoon.com

Here is a link that might be useful: Prairie Mooon Nursery