Foden has to start.
Opener against Iran and playing 2 DMs seems incredibly defensive and unnecessarily so. Against the nations which quite clearly have better attacks, I can understand.
I'd go with this:
Pickford
Trippier - Maguire - Dier - Shaw
Bellingham
Foden - Maddison - Sterling
Kane - Wilson
I can't see it happening in the slightest but I just don't see the need to go too defensive against Iran. I've put Trippier in but I wouldn't mind if it was TAA. Sterling more as a second striker
If Southgate does insist and stick with a back 3, I'd go with this:
Pickford
Stones - Maguire - Dier
Trippier Shaw
Bellingham
Maddison - Foden - Sterling
Kane
There's more than enough in the squad to tinker with and bring other players in that should be good enough to get the job done. For all the group games.