All three teams were drawn in Group B of the southern section with the final opponent to be confirmed.
The Groups, which are split into Northern and Southern sections, each currently contain three EFL Clubs with a fourth to be added on Wednesday 12 July when the 16 invited Under 21 teams are drawn.
EFL Clubs have been placed into their respective Groups in order to minimise overall travel for EFL clubs and fans following feedback from clubs. This process will be reviewed at the end of the season.
The Group stage fixtures will also be confirmed next Wednesday, with invited under 21 teams to play all Group games away from home.
Further information regarding dates, kick-off times and tickets will follow.