England head coach Eddie Jones has named five new players in a 35-man squad that will train together before the tour of Australia in July.
Wasps prop Biyi Alo, fly-half Charlie Atkinson, Gloucester flanker Freddie Clarke, Bristol back row Sam Jeffries and Exeter prop Patrick Schickerling are all included for the first time.
There are 16 uncapped names, with experienced players involved in the Premiership semi-finals not available.
Wings Jonny May and Jack Nowell return.
May has spent five months out with a knee issue while Nowell broke his arm during England's Six Nations defeat against France in March.
The three-day training camp is the second time in as many months Jones has called in a large contingent of uncapped players, having named 10 in a squad in May, as he assesses his options before the 2023 World Cup.
England play the Barbarians on 19 June followed by Tests against the Wallabies in Perth, Brisbane and Sydney on successive weekends beginning on 2 July.
Jones' side beat Australia at Twickenham in November but then produced a disappointing Six Nations campaign during which they were defeated three times.
England's head coach said the unavailability of players from Premiership semi-finalists Leicester, Saracens, Harlequins and Northampton presented "the opportunity to call up some new players".
"It's a great opportunity to learn about them and see what potential they have to play a part in the Australia tour," he continued.
England training squad
Forward: Biyi Alo (Wasps, uncapped), Alfie Barbeary (Wasps, uncapped), Jamie Blamire (Newcastle Falcons), Callum Chick (Newcastle Falcons), Freddie Clarke (Gloucester, uncapped), Tom Curry (Sale Sharks), Trevor Davison (Newcastle Falcons), Charlie Ewels (Bath), Will Goodrick-Clarke (London Irish, uncapped), Jonny Hill (Exeter Chiefs), Ted Hill (Worcester Warriors), Sam Jeffries (Bristol Bears, uncapped), George McGuigan (Newcastle Falcons, uncapped), Tom Pearson (London Irish, uncapped), Bevan Rodd (Sale Sharks), Patrick Schickerling (Exeter Chiefs, uncapped), Jack Singleton (Gloucester), Will Stuart (Bath), Sam Underhill (Bath), Jack Willis (Wasps).
Backs: Henry Arundell (London Irish, uncapped), Charlie Atkinson (Wasps, uncapped), Mark Atkinson (Gloucester), Orlando Bailey (Bath, uncapped), Joe Cokanasiga (Bath), Ollie Hassell-Collins (London Irish, uncapped), Will Joseph (London Irish, uncapped), Jonny May (Gloucester), Jack Nowell (Exeter Chiefs), Paolo Odogwu (Wasps, uncapped), Max Ojomoh (Bath, uncapped), Tom Parton (London Irish, uncapped), Adam Radwan (Newcastle Falcons), Harry Randall (Bristol Bears), Dan Robson (Wasps).