Papaver somniferum - Lavender Poppy
Consider a lawn of purple poppies.
Here's enough seed to plant a sea of lavender poppies, which will go on to make more seed and more poppies every year forever. Flowers are 2 feet tall on grey ruffled foliage, and blossoms can be 4" across. The pods that follow are fat and substantial, great for dried arrangements, and these are the seeds used for baking. You'll have plenty.
Papaver somniferum is an annual and can be grown in most every zone. Plant the seeds in fall and they'll sprout in spring. Come spring, you'll have thousands of poppy seedlings, which you can thin, transplant or leave alone.