Thomas & Rebecca

The paper used in the invitations is made by a local couple who started a unique business, Of The Earth. One of their specialties is paper which contains wildflower seeds, and your invitation is made from just such paper.

This paper can be put directly into the dirt in a pot or in your garden. The soil should be firmed down after sowing and the seeds should not be more than ⅛″ deep. They must be kept moist for 4–6 weeks and receive 4 hours of sunlight each day in order to germinate properly. Many wildflowers are drought tolerant once established but must receive adequate water as they sprout.
—text from Of The Earth

The seeds are a mix of annual (a) and perennial (p) species from North America which tolerate partial shade — they need 4 hours per day of direct sunlight — and grow to about 3′ (via):

You can see more beautiful paper from this Seattle business on their website.