There doesn't seem to be an exact equivalent term in English, but here is the wikipedia site defining the term and an EN language website where the term is used as is. I'd add a note (summer-blooming wildflowers growing in grain fields). In US agriculture anyway, such plants would simply be called "weeds". The bleuet (Centaurea cyanus) is known as the cornflower or, in the US at least, bachelor's button.