A source tells E! News William, 31, and newly single Harry, 29, both left town Sunday.
Before departing, the royals watched their friend Guy Pelly and his fiancée Elizabeth Alleen Wilson, granddaughter of the Holiday Inn Hotel founder, exchange vows.
The 32-year-old British nightclub owner and entrepreneur married his ladylove Saturday, and his best buddies gave the nuptials a royal touch.
Once the ceremony was over, the Duke of Cambridge went up to the bride and kissed her on the cheek, then he gave Pelly a big hug.
Next, wedding attendees headed to an outdoor cocktail hour as the sun was going down.
"Everyone was chatting and talking as they toasted their glasses and congratulated Guy and Lizzie," (pictured below) a source exclusively told E! News.
"Harry looked a little bit tired and was yawning over and over. He was also happy to be hanging out with his buddies and was having lots of good laughs as the evening went on."
On Thursday night, William and Harry enjoyed some good old-fashioned Southern barbecue from Charlie Vergos' Rendezvous restaurant in downtown Memphis.
Mr. Vergos, who owns the popular eatery, told E! News the princes were part of a group of 175 people or so who flew in for the Pelly-Wilson wedding party.
"There were about 20 couples in attendance," he said. (Kate Middleton stayed back across the pond with Prince George, and Cressida Bonas is sadly no longer part of the picture, so William and Harry were both flying solo for the fete.)
The royals were also given a private tour of Graceland, Elvis' former home and estate, which now functions as a museum and memorial to the Southern superstar. Princess Beatrice and Princess Eugenie also reportedly paid a visit to the late music mogul's home turf. Sounds like the Brits received a warm Southern welcome!
Additional reporting by Senta Scarborough