There is speculation on the Jacksonville Jaguars site that Dallas may be interested in franchised safety Donovan Darius.
This seems little more than a wild hypothesis. While the Cowboys clearly want a safety to complete their secondary, Darius is a strong safety; the Cowboys are looking for a free safety so that Roy Williams can be moved to his natural strong safety position. Darius would also cost Dallas a high draft pick or a player. With Dallas still negotiating for Darren Howard, it seem unlikely that it would try to trade for two players.
Lastly, Darius would want a long-term contract for a sizable amount of money. The Cowboys have cap room available, but it seems unlikely they could afford to pursue both an end and safety and have much left over for the draft.