Uncapped quintet Jarrad Branthwaite, Curtis Jones, Jarell Quansah, Adam Wharton and James Trafford have made Southgate’s initial selection.
Everton centre-back Branthwaite, 21, was key in his side securing Premier League safety this season, while Liverpool centre-back Quansah, 21, and 23-year-old team-mate Jones, who plays in midfield, helped the Reds finish third in the top flight.
Wharton, 20, impressed at Palace following his move from Blackburn Rovers in the winter transfer window and his team-mates Eberechi Eze, Marc Guehi and Dean Henderson have also been included by Southgate.
Trafford, who did not play for Burnley after being dropped in March, received his first England call-up in March after Sam Johnstone dropped out of the squad through injury, but has yet to play for the national team.
Other players to make the cut are West Ham forward Jarrod Bowen, Manchester City winger Jack Grealish and Brentford striker Ivan Toney, along with Manchester United midfielder Kobbie Mainoo and left-back Luke Shaw.
Mainoo, 19, played in friendlies for England against Brazil and Belgium in March and has made 31 appearances for Manchester United this season, scoring four goals.
Shaw has not played since February because of a muscle injury.
The training squad will join up on Wednesday, 29 May prior to friendlies against Bosnia-Herzegovina on 3 June and Iceland on 7 June.
Southgate’s side will then open their Euro 2024 campaign with a Group C game against Serbia in Gelsenkirchen on 16 June.