I do a lot of gardening with kids, they have magic fingers.
If my teacher said that over time the introduction of seeds being blown into a meadow by kids was responsible for seeding the meadow, you had better believe it. This lady knows her plants--she is a botanist. She is also president of the Maryland Native Plant Society. I can attest to the number of plants, I was not a participant of the summer camps. But, I have taken natural history classes at that location for several years and spend time walking the grounds.
This is my instructor who told me about the kids planting the seeds. She was the one who collected the seeds for them to spread:
Cris Fleming, Montgomery County
President, MNPS; field trip leader for MNPS, Virginia Native Plant Society, Audubon Naturalist Society, and The Nature Conservancy; instructor in the Natural History Field Studies Program, USDA/ANS; former Natural Heritage botanist/ecologist; principal author of Finding Wildflowers in the Washington/Baltimore Area; as President, member of all committes, and especially active on the Botany Committee.
Recently Fairfax County seeded a slope at an elementary school to create a wild meadow for the school. The area was graded, then seeded. This fall I noted that the common milkweed had germinated and was growing.