There are usually three to seven types of greens for sale- huge two hand bunches for a dollar. I'm terribly unclear on the names (and occasionally the families) but I tend to prepare them all the same way:
Chop one slice of fatty bacon into small bits. Fry on medium-high heat until crispy. Add one bunch chopped greens and stir until greens are tender. Serve.
Sometimes I fry a little onion or garlic with the bacon. Real vegans could just do that and add some oil. I sometimes garnish with lemon juice, chili paste, green onions, or cilantro.
As a pro tip- Ipomoea aquatica is absurdly tasty, the stems of bitter melon and chayote are not.