Although breadseed poppies and opium poppies are in the same species and look very similar, it's legal to grow your own poppy seeds.  Many websites will tell you otherwise, though, so I was afraid to try my hand until I found culinary poppy seeds being sold by a reputable seed company.

Growing poppies is pretty simple, but I've learned a few tricks over the last couple of years to increase yields.  Unlike most ornamental poppies, breadseed poppies aren't hardy enough to be seeded in the fall here in zone 6, so you should instead scatter the tiny seeds lightly on the soil surface in late February.  If you live in a warmer climate, you might get away with seeding in late autumn.

In 2010, I sowed my seeds too far apart, so this year I planted more heavily with the result that the seedlings formed a solid mass of green across the bed by late April.  That seems to have been overkill --- fewer poppy seeds came up on a different bed, and these better spaced seedlings resulted in much larger pods.  I suspect that the optimal distance between plants would be about four inches in a highly productive, no-till garden, although extension service websites suggest 6 to 8 inch spacing in a more conventional garden.  If you're going to overplant and thin, remove the extra seedlings by March or early April --- I thinned later than I should have in the photo above.

Your breadseed poppies will be in full bloom in June, and your honeybees will love them.  Besides keeping the plants weeded, you don't have to do anything now until the pods bulk up and then turn brown.  At that point, snip off the seed heads and bring them inside to dry.

Once the poppy heads are entirely dry, tiny holes near the top of the pod will open, so it's technically feasible to shake mature pods in a paper bag until all of the seeds fall out.  In practice, though, it's much more efficient to pound the pods to crush them, tear the heads open a little more with your fingers, and then shake out the seeds from one pod at a time.  This really doesn't take very long if you've just grown a small patch of poppies.

Poppy seeds are too small to winnow easily in front of a fan, but you can remove nearly all of the bits of chaff by sending the seeds through a sifter.  Let the seeds dry a bit more in an open container, then seal them away for winter treats.  I've discovered that if I paint raw egg on the top of homemade buns before their last rise, sprinkle on breadseed poppies, then mash the seeds into the dough with the palm of my hand, nearly all of the precious seeds stay in place and the plain old bread turns into a treat.  I figure this year's quarter cup harvest will last all winter.