Years later, dating the Finnish woman who is now my wife, I learned how to gather nettles, about nettle soup, and even that eating nettles can de-sensitize you to seasonal allergies. I had completely misinterpreted that part of Solzhenitsyn's writing, and that his point was that at least when the nettles were growing the gruel had some additional nutrition (like vitamin c) in it.
A lot of knowledge like this has been lost in suburban America.