From Military Times:

“As of September 2013, all Naval Special Warfare personnel are authorized to wear the U.S. flag and the “Don’t Tread on me” uniform patches,” Navy spokeswoman Lt. Cmdr. Sarah Flaherty told Navy Times. “In the past, NSW did not authorize wearing either patch unless one was deployed or in a work-up cycle. However, NSW recently sought special permission from the Chief of Naval Operations staff to wear the patches within the continental United States.”