Let's talk about kale.
One of the things I love most about the Northwest is that I can find fresh organic leafy greens, year-round. Kale, especially, is readily available in your local market from mid-winter through early spring. This time of year kale is especially sweet and tender. I came fairly late to kale, as a cook. It wasn't one of the greens I remember my mom cooking, when I was growing up in Montana.
Kale and collard greens are old plants, cultivated in kitchen-gardens for nearly as long as we have records. Described by 1st century writers, the Romans and Greeks grew greens very similar to modern kale and collard. Either the Romans or the Celts introduced "coles" to Britain.