Thanks to reader heatherleann, I now know what the spiral-twig things are that I might want in my flowers! They're called Fiddlehead ferns.
Picture search results show varying colors, from lighter brown/green to dark purple/black. Just like black dahlias, there is no true "black" in flowers, just the dark dark dark burgundy color.
Below is an example of a few in a bouquet similar to what mine will be, color wise.
Here's a close up. Aren't they so simply dramatic!? I might have to choose between these and black dahlias, or there could be too much. Or, I could utilize them in the bridesmaid bouquets?
I'm so glad I won't sound like a bumbling idiot at my florist appointment on Saturday! Score! Thanks so much heatherleann!