I have grown a couple types of the annual poppies (California and breadseed). I am not sure they have much nectar, because I've never observed a butterfly on these. However, the breadseed poppies must have fantastic pollen, because the bees went absolutely nuts when these were blooming. There were sometimes 4 or 5 different bees on a single flower, rolling all over the pollen anthers. I've never seen that many pollinators on the California poppies.

Don't know about the perennial poppy species.