Having grown up by and large on canned vegetables, greens of any kind were not something I learned to appreciate. My mom seemed to have a love of canned spinach, but I just couldn't develop an appreciation for something that was limp, olive green, and salty.
Somewhere along the line, and I don't recall when, I got reintroduced to proper greens. Then again, now that I think about it, it might have even started as spinach in a focaccia panino sandwich. I remember being really shocked at the difference and impressed at the flavor and texture difference. I've been a big fan of fresh spinach ever since. Aside from steaming it, I often enjoy it raw in salads or sandwiches, and will often use it in place of where I would otherwise use lettuce.
Another recent addition was a green that gets proverbially tossed around a lot with its association to Southern Cooking or soul food. That of course would be Collard Greens. These large flat slightly bitter leaves cook up nicely in a variety of ways. My favorite thus far is to strip the leaf from its stalk and center vein, and then roll up the strips and slice them into thin strips. I then toss a minced clove or two of garlic into a hot pan with about a tablespoon or so of olive oil and let it sizzle for a few moments. Then I toss in the big pile of greens and stir and toss regularly until the strips turn a bright green and just begin to wilt. I season with a little salt and pepper, and it is also very common to add a dash of your favorite hot sauce. I often use collard greens to otherwise dress up a dinner of boxed beans and rice or jambalaya. In addition to tasting good, they are high in Vitamin C, folate, and soluble fiber. Good stuffs!
I'm still learning to appreciate others. Kale and I still haven't come to any agreements, but I truly think it comes down to texture. These firm and tart leaves have a lot of cooking possibilities, but I haven't yet found an appreciation. I hear really good things about mustard greens and even greens from things like radishes and other root vegetables. I'll be investigating others over time.
Regardless, I've come a long way from canned, and I really enjoy the opportunities to rediscover fresh versions of things I only experienced preserved in such a way that it would feed the roaches at the end of the world. :-P