When poppies are done blooming, the petals will fall off. What is left is a pod with sort of a lid on top. When the pod turns brown and the "lid" on top is opening, cut off stem with pod still attached. You can shake out the seeds like a salt shaker for seed storage. If you don't do this as soon as they turn brown, a strong breeze with cast out the seeds for ya :)
thanks--so nice of you to include a picture! since you are knowledgeable i will ask one oher question--my pomegranite bush has "hipps" as in rose hips--i don't really know what they are--is it the seed pod?
there are fishing boxes with the plano name--not sure if they are made here---good thinking about the seed saver boxes--maybe someone needs to design such a thing? i want someone to invent something very easy to sort of lift up the compost pile and let the air in--i stick branches in mine so it doesn't pack down but idon't think that works very well