The Ferrero Group said Thursday it will buy WK Kellogg Co. in a deal valued $3.1 billion, expanding the Italian food giant's global reach. Kellogg, which was founded in Battle Creek, Michigan, in 1906, is known for brands including Corn Flakes, Froot Loops, Rice Krispies and Special K. Ferrero's brands include Nutella and Rocher chocolates.