These buttery thumbprint cookies combine Oregon grown hazelnuts and Marionberries. Start with little balls of chilled dough, create a “thumbprint” indentation, dip in sugar and nuts, and then fill with jam. The taste of hazelnuts and sweet Marionberry jam is an absolutely perfect taste combination. Hazelnuts are grown primarily in the state of Oregon in the USA, along with Turkey and Italy. Marionberries are named for Marion County, the Oregon County where they originated. Marionberries, a cross between Chehalem and Ollalie berries, were developed by Oregon State University's Agricultural Research and Development Program in Corvallis, Oregon, beginning in 1945, and finally introduced in 1956.