Hi,
Your seeds are definitely from something in the Asteraceae (Daisy) family, but I dont think they are mature. Was the flower thoroughly dried (and probably somewhat puffy, like a dandelion seedhead might be) when you harvested it? Very often I find that seeds of plants from this family in the seed exchanges like the NARGS are in fact infertile because they were harvested too early, or because some plants in this family are self sterile (these require another clone [genetically different plant grown from a different seed] to set fertile seed).
The little thingy on top of the parachute is a part of a disk flower (the "petals" of daisies represent individual ray flowers), specifically it appears to be the female part (pistil). Generally if Asteraceae seed is ripe and fertile, it has shrivelled and dropped off by then so only the parachute would be attached to the seed. Its presence does not hurt the seed, but I suspect the seed shown is not viable anyway. To complicate things slightly, some Asteraceae like silphium and dahlias tend to produce "dummy" seeds that are infertile among the fertile ones. These are thinner and lighter than the fertile seed.
You can easily test seed from Asteraceae family members to see if they are viable by letting them sit for a couple of months (this is called afterripening and some seeds need it) then sow some on a moist paper towel in a ziplock bag. Set in a place where it is exposed to light (but not in sun as that might cook the seeds) and most kinds of Asteraceae seeds will germinate within a week or so. They generally do not require chilling like some other seeds, but may require light to sprout.
One way to become familiar with what is immature versus mature seed is to open up fresh and recently faded flowers of any of the following Asteraceae, and compare the young "seeds" you see with what you find in seed packets or completely mature, naturally dried seedheads of such flowers as zinnias, marigolds, sunflowers, and dahlias.
Hope this helps, and good luck!
Ernie
