Rugby union star David Lyons has appealed to thieves to return stolen memorabilia, saying the items are valuable to him but to no-one else.

Awards and match jerseys belonging to the Wallabies and Waratahs No. 8 were stolen from his father's four-wheel drive in the Blue Mountains, west of Sydney, on Monday night.

They include his 2004 John Eales Medal - awarded to whoever fellow Wallabies judge as the best Test player of the year - as well as three Australian and NSW jerseys embroidered with match details.

Lyons is moving to Wales to play rugby union for Llanelli in the coming months, and his father had travelled to Sydney to collect some of his belongings.

"My father came down from the country and took a lot of stuff that he's going to store for me at his house," said Lyons, 27, who grew up in Molong in the NSW central west.

"He stayed at his friend's place in the Blue Mountains overnight at Springwood (on his way home).

"I think he (Dad) has taken it pretty hard," the 44-Test veteran said in Sydney.

He appealed for the items to be returned, saying they had sentimental but no monetary value.

"Just give it back, there will be no harm done," he said.

"It's something nice for me to hold on to for my kids ... it is no value to anyone else."

Lyons is optimistic he'll get them back.

"These things happen," he said.

"You never know, hopefully they'll turn up," he said.

Police are appealing to anyone offered the items, including memorabilia shops and auction houses, to contact Crime Stoppers on  1800 333 000.

AAP