Sandbur
https://www.inaturalist.org/observations/76275274
Coastal Sandbur
Cenchrus spinifex
Cenchrus echinatus would have an inner whorl of big bristles with flat bases surrounded by smaller roundish-based bristles. The bristles here are all about the same size and have flat bases, like C. spinifex.
Photo 4 of this observation is a good example:
https://www.inaturalist.org/observations/18483664
