I don't think there are many on the list that I haven't tried. I find there is a much wider choice available here in Canada/US, than what I was used to back in the UK. I love going into my local fresh produce grocery store and finding something new to try.
The only one I don't think I would try is fiddleheads, unless someone tells me they are delicious, as just the look of them scares me. lol
As well as superfree foods, there are so many different grains, beans, pulses etc out there too, but how many of us stick to just the usual rice. My newest favourite grain is Millet. I am making a pilaf tonight with some. It has great health benefits too and very yummy.
Sorry I went a bit off from your topic of Superfree, it is surprising what one subject can get you thinking about. lol
Feel free to wander off my topic - I am always wandering off other people's, so I can't complain!!
Fiddleheads are strange, aren't they? (See picture below for those, like me, who hadn't heard of them before.)
I don't think I have had millet - can't remember. Quinoa is one grain I have tried recently and it was very nice.