Hi Katie,
I was hoping someone would answer this for you as it seems an interesting problem.
And I have no personal experience with this species but find some Helianthus to either hold their seeds tightly or have a sap that will do so.
My solution is to immerse the seed heads in a bucket of water for the morning (holding them under the water with a handy brick) this loosens what holds the seeds. I can then easily breakup the heads and remove the seeds. Yes this can be messy. Dry well on a plate and there you go.
Maybe try just one head to see how it works.
Hope this helps.
Brian

Thanks for your help Brian.

I learned from another trader how to collect seed from Narrow-leaved sunflower/Swamp sunflower - Helianthus angustifolius. I came across a member's Trade Page when she responded to my Post: Have Sourwood tree seeds, thank goodness! I love these yellow October flowers, added two other smaller varieties with double flowers to my Wish List, so I knew somebody had to have the answer.

When I e-mailed, asked how she did it she responded,
"The swamp sunflower seeds -- they will be ready 3-4 weeks at the earliest after the flowers are done blooming. Just take off the seedhead and crumble -- the seeds are small, dark and slender."

Now I can fulfill a couple pre-arranged trades and feel comfortable offering them for trade again next year!

What would I do without the collective experience of folk on GW?

Happy Holidays!
Katie

May I ask how brown are the seedheads supposed to get before you can pinch them off the stems? I don't want reseeds of this plant, but I do want to save some seeds. I pinched what I thought was a very dry and all brown flower, but when I did a check inside, I didn't see any indication of black, just dry, straw colored sticks. Did I pinch the flowerbud too soon? Thanks - Carrie