I don't know if radishes are the way to go if you have heartburn - but then, I only have anectodal evidence. My dad loves radishes but eats them sparingly because he says they give him heartburn.
As far as veggies go - some pretty standard ones that you didn't put on your list are broccoli, cauliflower, spinach. Zucchini and yellow squash too.
For less standard ones, and I'm not an expert and certainly not much of a cook, I like beets. You can eat the red part - I like to steam them and just eat them that way, no need to add anything. And you can eat the greens too, just like spinach or something. (And you can eat the stalks, but I don't always).