Metal Arch Metal Arch Things On Indiana Farms That Say "Valley"?

Metal arch things on Indiana farms that say "Valley"? - metal arch

While driving through northern Indiana, I saw several large arc-like structures in agricultural holdings, which never before seen in the areas of New York. Seemed bridges, small, thin metal, with more than three or four peaks and valleys. Ran perpendicular to the street and at least one had a sign saying "valley" in them. What are these?