I have kale (siberian and red russian), Georgia collards, purple top turnip greens and spinach planted in separate patches, some like them mixed. some like them individually, kale is the new trendy health food and very popular.
Of course like DC mentioned there is poke salat, a wild toxic weed that sprouts up in the spring along back roads and paths. It has to be boiled several time and the liquid poured off to be safe to eat. It grows in abundance along the exercise path I use so I stockpile some every spring.
Most cook it down and season it in a pan then break an egg in the mix, tastes like cooked spinach.
I get creative with it; here is some cooked in chicken stock with onions, garlic and wild chanterelle mushrooms.