Hi,
The seeds are like the in the link below. Vernonia(Ironweed) seeds all seem to have the same shape though the size and amount of tail looks to vary between species.
Remy

Here is a link that might be useful:

Thanks Remy. I have a whole field of it behind my house. Butterflies love it although it is not an especially pretty plant. Each flower head will then have multiple seeds. Each one with a tail correct?

Hi again,
Yes, each one will have a tail. I call these types of seeds shuttlecock(Badminton birdie)kinds. I'm not sure if that is a correct term. I believe I have heard/read others use that name to describe this type.
Remy

Oops, forgot to add, you will get traders who want these seeds to attract butterflies, definitely!