Hi Pink Petunia,

See if the picture at this link helps. Rudbeckia seed can be hard to tell the difference--probably about half of what you have is chaff and half--or less--is seed. You can often "feel" a difference between the two--the seed has more "substance." If you start looking really closely, you'll be able to tell the difference, but it's a terrible job to try to separate them! The easiest thing to do is to leave it all together and plant a little pinch of it---some will be seed and some will be chaff. If you want individual plants, you can separate them after they come up and have a couple true leaves. If you're going to trade it, just be sure it's clear that the package you send will contain both seed and chaff. That's what I do with my Echinacea.

Skybird

Here is a link that might be useful: Seedheads, seeds, & chaff -- Rudbeckia