Will the seed pod on peonies grow more plants? If not, what should be done with them?
Many of the old varieties of Peonies will generate viable seeds though the hybrids likely are sterile or if they are viable would differ from the parent plant.
You can harvest the seeds in August, they should be starting to turn dark brown and just be cracking open.
Direct sowing in the best method and you can do this with the seeds that are freshly harvested or if left to dry to nearly black seeds they then can be direct sowed into the garden.