Narrow green stem about a foot-and-a-half tall, ending in a cluster of green spikes pointing straight up. I’ve seen it before near a lagoon in Encinitas (San Diego County). The docent there showed me you can remove a spike and peel of a bit of greenery around its base to reveal a ring of polyp structures. You can then pry up one of these polyps and use it to tear a vertical strip off the spike. Holding it up by the polyp, you can then watch the strip spin counter-clockwise until it has wound itself into a corkscrew. I’ve got them in my backyard now, but I just can’t remember the name.
I think I know what you are talking about. You take the weed spike and twist it and the “leaves” form a spiral.
Is it some sort of filaree?
I’ve got an infestation of that shit in my front yard.
Yes, that’s it. White-stemmed filaree is probably the one I have. I don’t know about twisting the spike. What I do is peel off one of the five segments and hold it up. You can watch it spin around until it winds itself into a corkscrew. That’s a cool trick that compensates in a way for a yard full of weeds.
Filaree is a pretty interesting plant. Native to the western states, so it’s not technically a weed. It’s a superior ground cover and soil stabilizer and valuable forage for wildlife & livestock…it’s actually seeded into some pasture land and one place I worked was experimenting with it as a ground cover for orchards and vineyards. The corkscrew action in the mature seeds serves to drill the seed into the ground to aid germination and rooting. It’s pretty neat (if one is into that sort of thing) to pluck a couple of mature seeds and watch them twirl themselves into the dirt. Nature’s own seed drill at work 
SS