The plant below is Lunaria annua, better known as "Honesty".
This is a beautiful flower, easy to grow, and very forgiving to the novice grower. It self-seeds freely and fills the garden willingly with flowers, with very little effort from the gardener.
We all know the honesty plant when we see it. It is the one that produces these amazing seed pods, which are completely transparent. Initially the pods are green, but as they mature, it is possible to peel off the green outside layers, and reveal the beautiful translucent section, with the seeds visible in the middle.
Honesty lives for two years, flowering in the second year, but once a population is established in the garden it self-seeds so freely that the garden is never without these flowers.
What could be better?