They're all different, and they're all cool.

Here's a few samples:

Pic: Filipendula kamtschatica seed.

Pic: Filipendula rubra seed.

Pic: Filipendula ulmaria seed.

Pic: Filipendula vulgaris seed.

I first noticed the seeds of our wild one, Filipendula ulmaria. They're cool. So I looked at the seeds of other species - they're cool, too.