Pretty much any type of green can be sautéed. Here is a good recipe for swiss chard.
Different green's should be cooked for different length's of time and some should have the hard stem completely removed. For example, spinach is a quick saute or it turns into that green slime like the frozen stuff. Swiss chard needs to have the stem ends removed, then cook the rest of the stems longer then the leaves (just dice it up). Kale or collard greens should have the stems totally removed.
Whichever is available, just saute it with some garlic. Finish with a bit of balsamic maybe. Or add turmeric, cumin, or fennel seed. Lots of options here. Cheap and healthy complement to most any protein. I'm fiddling with different combinations depending on availability.
There was a really odd story on NPR a few weeks ago about a guy foraging for wild greens in D.C. If you have ever wandered around the District you may wonder what kind of disease you are likely to contract by eating whatever is growing around town, but the story did point out how easy it is grow healthy greens with just a bit of knowhow. The piece also featured a biologist who discouraged anyone from eathing things growing in the wild unless you really know what your doing because:
“Poison hemlock and wild carrot look alike,” Kallas says. If people haven’t studied the plants, it’s easy to confuse the two. “They find something that they think is wild carrot. It’s actually poison hemlock, and they eat it and then they die.”
If I had some land and a garden I would plant some green's, but only from trusted seed that I know for sure isn't hemlock.