How/When to Harves Black Eyed Susans?

This is my first time harvesting seeds from by Black Eyed Susans. Does anyone have any advice on the best method & time for trying to do this? I'm getting a lot of black pieces as I rub my thumb over the black center ball. Some of these pieces look like seeds ~ others look useless! Please help me!

Don't worry if you get some chaff. When you sprinkle it all on the ground, the seeds will grow and the chaff won't bother anything.

And you can run your thumb over that seed head an awful lot of times! Might just as well rub it bald if you want to catch everything.

Thanks! I thought I would go crazqy! I even started to pull the ??? from the ball with tweezers, but those certainly didn't look like the possible seeds I was gettting by just rubbing my thumb over black eye ball. Thanks again!

Thanks! I thought I would go crazy! I even started to pull the ??? from the ball with tweezers, but those certainly didn't look like the possible seeds I was gettting by just rubbing my thumb over black eye ball. Thanks again!