As craft whiskey producers look for ways to improve their products, many are looking to the past, bringing back varieties of grain that have been largely lost from the country’s fields. Dad’s Hat, a Bristol, Pennsylvania-based craft whiskey producer is working with Delaware Valley University to bring back Rosen rye, a variety that was widely grown in the U.S. about 100 years ago. The University harvested a batch of Rosen rye on July 16 that Dad’s Hat will use to create a small, test batch of whiskey this summer.