Yep looks like Red Russian Kale which I've been letting go to seed and they self seed everywhere. Very good eating. Young leaves are good for salads and older bigger leaves for kale chips and sneaking into smoothies for the kids to drink their veggies.
They particularly liked Banana, Kale, Kiwi combo. Recently, DD said, you added kale didn't you? The smoothie wasn't this green -- it was more like pale yellow -- when I saw it last, then I walked away and now it looks greener! But they loved it anyway. This one was banana, mango, and avocado + kale.
...and I was thinking Turnip for that other one.
I wouldn't keep the tomato volunteers if there is a high probability that they are from grocery store tomatoes. However, most of my tomato volunteers could be any number of specialized heirlooms and I would love to keep them all -- I just don't have the room. I always hesitate especially when they are potato leaf seedlings....
I posted about this year's exciting tomato volunteers I found among the radishes -- these could be one of a handful of somewhat rare variegated varieties I've been growing in the last couple of years:
Cucurbits take up so much space that I hardly ever let the volunteers grow, but I've ended up with some very nice pumpkin and squash. Again, mostly because that's what I've been growing. But if the seeds had come from Halloween jack-o-lantern carving, the field pumpkins could have crossed with fall decoration gourds, etc. But again, I generally let a few grow every year if I have the space, just to see what they might be.