Cottager's Kale
A legendary kale from Britain with huge purple leaves on a tall sturdy stalk. Some plants become perennial. The plants get very large, and are very cold-hardy. This was a mainstay source of food for people and their animals for centuries until global food transport eclipsed the traditional food system. It's time is coming again, though. Not as reliably perennial as tree collards, but more reliably frost-hardy (and grows from seed instead of cuttings, so you can have more plants.) It does have a strong reputation for a higher proportion of perennial plants than other kale, but performance will vary from plant to plant and garden to garden.
I am not aware of another US source for this. Ellen Bartholomew, who farms with a focus on year-round food for the community, produced our seed. 80 seeds