Collecting seed can be very helpful to the local plant population. A S. purpurea's seeds get distributed over a very small area, so if you collect a seed pod and distribute half of the seed around the bog and keep half, you've helped that plant's reproductive chances, even though you've left with some seed.
When I lived in Maine, I'd take a ripe Trillium seed pod if I came upon a few during a day in the field. I would leave seeds here and there as I did my thing. I never kept any, but just did a Johnny Trilliumseed act. I think Trilliums ordinarily rely on ants, not geologists, to scatter seeds. It isn't a perfect method, but ants do carry them undergound.