A Norse settlement from about the year 1000 has been excavated near the northern tip of Newfoundland, at L’Anse aux Meadows. The items found there are definitely of European origin, not Native American. Of course the settlement doesn’t seem to have lasted very long. It isn’t clear if any of the Norse explorations reached the areas that are now part of the US. There was a medieval Norwegian coin found in an archaeological site in Maine, but perhspa it was traded from one tribe to another, so perhaps was acquired through contacts in what is now Canada.
The Norse settlement was primarily a trading post- they engaged in commerce with the Innu and Inuit, exchanging metal tools for walrus ivory. A similar pattern emerged when the English arrived here, trading manufactured goods for fur. North America’s oldest corporation, the Hudson’s Bay Company, was established by Royal Charter for the specific purpose of supplying Europe with furs.
The Vikings supposedly loved this berry and took starts with them wherever they went.
If you want to know where Vikings went in North America, I'd start at Shinnecock.
Thank God, they were not Lutherans. Hah!