Much like how poppy flowers are used in the United Kingdom and Commonwealth countries, cornflowers -which also grew on battlefields even after being churned up by artillery fire- are used in France to remember WW1 and generally as a symbol of solidarity with veterans.
While poppies were chosen following John McCrae’s 1915 poem, cornflowers became linked to the Great War in 1916 when Suzanne Lenhardt and Charlotte Malleterre, a war widow and orphan respectively, set up small workshops where mutilated or otherwise incapacitated soldiers returning from the war could work on making fabric and paper cornflowers to sell on the street as a way to reinsert themselves into society and make some money.