Sea kale Crambe maritima is sometimes referred to as the King of the Vegetables (Queen is perhaps more fitting!) . This is partly due to the fact that it was in the past cultivated in heated greenhouses for nobility in the UK for Christmas! Maybe not the King, it is certainly an aristocrat and the easiest perennial brassica in cold climates (along wtih even hardier Crambe cordifolia) as it is hardier than perennial kales as it resprouts from the roots every spring and can easily be covered by a mulch of leaves or suchlike in colder climates. I do this every autumn just in case we have a very cold winter (I have experienced plants to resprout from deep roots when the surface roots have been killed in winter). I would normally take off the leaf mulch early April, but this winter it’s been so mild I removed it a few days ago and the plant had already put out delicious sprouts…I’ve been snacking on them! My oldest sea kale is approaching 40 years old, but hasn’t appeared yet (oldies sleep longer I guess!). Much more about Sea Kale in my book Around the World in 80 plants or by searching here: https://www.edimentals.com/blog/?s=sea+kale
They are also beautiful. The pictures show the cultivar Lily White which is only about 8 years old.