Of course they're food! They are no doubt healthy because they are so fresh. I used to pick fiddleheads with my grandfather in the spring. We would also go looking for wild asparagus and giant puffball mushrooms. The puffballs were my favourite because we would slice them and fry them in butter. If you were lucky enough to catch a spring smelt run as well, you were in for a gourmet meal!
I've never tried fiddleheads but they grow nearby. I have to pick some and try it out as a side dish.What I did try is dock. My mom used to make a tasty soup with its leaves.
I also loved cakes with rheum. You should try it, tastes a bit like lemon.
I've never tried dock but we had some rhubarb (rheum) growing in the yard which we used exclusively for cakes and pies (not the yard BADecker but the rhubarb). Rhubarb pie is delicious.