Here is a March photo of poppies that have self seeded in my front yard garden. It is always nice to have a lot of volunteers, but this is just too much. In a couple of weeks, I will thin these out, either by pulling them out from the root, or if the roots are intertwined, I will cut them off with a scissors. I could try and transplant these guys, but that would have to be done immediately or they would not live through the transplant shock.
Poppies don't seem to mind being crowded together, so I won't be doing a lot of thinning. If you want to control the poppy bloom height, you can cut the tops of the plants now. This way they will not grow as tall before they bloom.