Are you talking about what we think of as breadseed poppies?

I have the breadseed poppies and as soon as the seed pods mature (this is about early July) I collect some of the seed and then rebroadcast in the fall on unmulched soil. They also need to be sown in an area that receives full sun. Mine aren't too picky about the soil as long as it's not wet.

And then beginning next May, the new seedlings begin pushing up. I don't water them, I just let the natural rainfall here in the Midwest take care of things.

You just repeat the process of saving some seed every year.

Hope this helps,