Crambe tataria. Tartar bread plant is an inland relative of sea kale and can be used in much the same way. Although it was traditionally harvested for its roots, which can be dried and ground into meal, I think the leaves may be the more interesting part. Think of this as a sort of perennial mustard green.
Tartar Bread Plant does not grow true from seed, but this mix comes pretty close. There is some limited variation is the size of the leaves and how lobed they are, but they are almost all smooth leaved, lacking the prickly leaf hairs that some plants have. There is probably more variation in the lifespan of these plants. We have some in their fourth year now, while others have set seed and then died in their second year. We will be introducing some improved, strongly perennial varieties propagated by thongs, but if you are willing to tolerate some hit and miss with the perenniality, you can get some nice plants from this seed.
20 seeds. We have not removed the cork shell from these seeds, which means that there are probably some that are empty or poorly developed, but our total germination rate has been over 80% without removing the shells.