Without having more plant parts (foliage, or during the right season, flowers) to help ID the plant, we can't identify the species from seeds alone. If you see the plants regrow in that area next year, feel free to send photos as it reaches flowering age and we can then try to ID it.

Miri

Understood...then unfortunately we can't ID them unless some turn up still inside the seed pod/capsule or the seed head from the flower that produced them. There are hundreds of possible plant types they could have come from, ranging from a variety of weeds to annuals, perennials, shrubs, trees, and vines, especially since they might have blown in from several yards away.

The only other option is to try keeping them for the winter and sowing them in spring to see what emerges. It would be an experiment, since we don't know if they need a cold dormancy period (like being stored in the fridge) we can't tell since we can't ID them, nor would we know how deeply they should be sown (you could try some at the surface and some slightly buried, such as a quarter-inch or half-inch deep). Some seeds must be stored humid/moist while other species tolerate drying out, so this too is a trait we can't determine. Once germinated and a few true leaves (not seed leaves) are produced, we might be able to recognize what plant group it belongs to, if not what species. If they belong to a biennial or perennial, they will not flower their first year, but an annual plant would, which would speed-up identification efforts.

Miri