Retail giant J.C. Penney Company Inc. has sold its Plano headquarters in a partial leaseback of the three-story, 1.8 million-square-foot campus, which will help the retailer reduce its outstanding debt and manage its expenses. The campus sold to Silos Harvesting Partners LP, which is a limited partnership led by Dallas developer Sam Ware, for a total of $438.7 million, according to Collin County deed records.