People from other continents always surprise me with various fruits they taken for granted their entire life, but I've never heard about, and vice-versa.
Clearly, for instance Welwitschia (1) listed. I think this says a lot about location.
It's a fascinating plant, but it is an endangered species, endemic to the Namib desert. And as far as I know, not that commonly eaten.
On a side note there are 1000s even 10s of thousand of edible plant based species that grow on the earth. i don't know how old they are though.
I need to get food at the market, not wait for it to fall into a trap or fight it to death.
I'm having trouble finding sources for other specific fern species, though many ferns have been around for hundreds of millions of years.