The first bit below will sound off-topic (bear with me, it will make sense in a little while).
30 + years ago, when I was in graduate school (University of Georgia), I had a friend and fellow graduate student who was from Taiwan. He spoke very little English when he first arrived (learned English in school, but little practice outside of that). I clued in to this when he was mostly smiling and nodding, rather than talking. I did my best to be friendly and patient, keeping our conversations simple at first, easing into more complex conversations later on; we became friends, and he became more confident talking to others as well. By the time the calendar rolled around to Chinese New Year, I was an invited guest at a party at his apartment, the food included many Chinese dishes, not the fare you would get in a restaurant, but more like home cooking. I made a point of trying just about everything! Including jellyfish and "century eggs", but that is off topic.
I will never forget one dish though, just for one ingredient. A stir fry that included the tender newly-formed stems and leaves in new pea shoots (it was February I think; peas are full grown here at that time, but still producing new shoots). Flowers and older stems and leaves were omitted. The greens were wonderful! Briefly cooked, tender, with a light sweetness to them; I was an adult, and had never heard of eating the greens from peas before. This year, I think I will try them again, growing them in my own garden. There's plenty of online advice for basic preparation (like spinach, and cooked just a couple minutes).
There are other excellent greens from other plants. In the southern USA, turnips are grown as much for the greens as they are for the roots, or maybe MORE for the greens (at certain times of the year, you can get them fresh, or frozen, in grocery stores). Collard greens and mustard greens are also very common here. I grew a small bed of turnips, just for greens, last year. This year, I planted a bed three times as big, just for turnip greens (though I won't turn down roots if I get them). Young turnip greens, blanched briefly in salted water, are wonderful! Reading up on other uses for turnip greens, the youngest leaves are reported to be good in salad (I definitely will try that this year, a good use for small plants pulled to thin out a bed).
I have been doing some reading up on other greens (just plants where edibility and palatability are VERY well-documented). I've read that the young leaves of Swedes (our "Rutabaga" over here) can also be cooked like turnip greens. Young radish greens can also be cooked. Again, I am seeing opportunities to use greens especially from plants culled during thinning.
I'm curious, what other less-common greens have you tried? Any of the above, or others I might want to look into?