This:
It has several names in Norwegian. Raspeballer, klubb, komle are some. They are grated, raw potatoes that are mashed together with flour and salt into little balls and boiled. This is the most delicious thing ever. Often served with bacon and mashed swedish cabbage (like here), and often with mutton in stead of the sausage. And there has to be lots and lots of bacon fat. Maybe steam a carrot if you're feeling like a health freak. I like putting a little ketchup on them as well. (But my parents look at me like I engage in blasphemy when I do.) I don't know how this compares to what you call dumplings, but I recommend trying this (though most people hate it the first time they try). Must be served with cold milk.
and this:
This is lutefisk. Or directly translated, lye-fish. I don't know how well this fits the criteria of you not having heard of it. Living in Norway I feel like every foreigner has heard of this, but I could be brainwashed by the nationalist propaganda. It's cod, soaked in a combination of cold water and caustic soda for something like a day or two, until it gets a jelly-like consistency. This is to be served with potatoes, bacon, mashed peas and norwegian potato liquor. Neither lutefisk nor Norwegian potato liquor is any good, even most Norwegians will testify to that, so this I don't really recommend trying. I still eat it at least every christmas, though.