Yellow cabbage collards--we usually just call them "cabbage collards" are an old variety of collard greens much cherished in eastern North Carolina. They're not really yellow, though, more a slightly lighter green. The yellow cabbage collard has a different taste than what is called a green Georgia collard, it tastes similar to Chinese tender greens (Bok Choy) in my palate. It is more tender. It's got a yellow tint to it, and it's not as tough with a milder, less bitter flavor than regular collard greens.
 
Perennial, cut and grow. 

It is almost impossible to find this anywhere else in the country other than eastern North Carolina and me in SF Bay Area. 3 cuttings for $5. Tempting but not ready yet? No problem, we can wait. Please only approach when you are ready to pick up. And yes, you can plant any "perennial" veggies in SF Bay Area all year round. And it is TOTALLY your loss if you don't have this, it is perennial, grow like a tree, leaves are easy to clean (cut and grow), and it tastes so much tenderer than normal collard green.