What part of the white poppy contains the opium?
Wait until the petals fall from the seed pod, leaving a ball shape pod. Scratch the surface of the pod with a pin, very lightly (if you scratch too deep, it will ruin the opium) or about 1/12 inch. I thick, white sap will come out. That is opium. Let the wounds seep for a few hours. Come back and the opium should have dried, then scrape it off of the pod.