Nigella, larkspur, cornflowers are great for spring and early summer here in my zone 7b. Easily sown at the same time. I direct sow seeds for annual poppies and these annuals in November.

Cameron

Are you interested in companions that bloom at the same time as the poppies or something that blooms later in the year?

For late summer interest in my garden, nothing beats lilies, especially lilium "Black Beauty". Very easy to grow, but it doesn't take up much space unless it's blooming. I spread them around, wherever there's a "hole" left by spring blooming (and then vanishing) plants like oriental poppies and early-blooming annuals. When the lilies are finished blooming, they don't cast much shade on the re-emerging poppies.

Maureen