Unidentified flower

[Gazgoal]

Hi would really love to know what this flower is growing in my veg box if any one can help I would be most grateful cheers

 

[NigelJ]

Looks like a form of poppy to me. If you scratch or snap off a flower head do you get a white sap oozing out?

 

[Owdboggy]

One of the many forms of the annual Opium poppy.