Butterfly Weed (Asclepias tuberosa) is true to its name. It certainly attracts butterflies! And in this case the Great Spangled Fritillary (Speyeria cybele). It is also a very attractive, and beneficial, plant to have on the homestead. Butterfies are excellent pollinators, and are very elegant, and beautiful.
To collect some seeds in the fall, visit the plant while it has seed pods, and bring the seed pods home ( If it is legal to collect seeds in your area). When they are ready to plant, they are dry and fluffy, like other other members of the milkweed family. The seeds are attached to little fluffs of "cotton" which acts as a parachute to disperse the seeds using wind.
These photos are from last fall. I can't remember, for sure, but I think this is common Milkweed, which has very similar fruits, and seeds. This fluff is amazingly soft. You'd have to feel it, to believe it.
Later, take care!
All photos are my own