Meconopsis cambrica,

 

Meconopsis  cambrica, Welsh Poppy, schijnpapaver, pivot jaune (pictures)
 
Invasively self-sowing but delicately pretty yellow or orange summer-flowering Welsh Poppy. It is an easy to grow and reliable perennial .  They both exist :  single and double forms.  The double forms can only be propagated by division.
Position : sun or partial shade  Height 30 cm.  Blooming from mid-spring to mid-autumn   

 

Beautiful combination with crocosmia masoniorum