Hi Nancy,
Carrot seed and other plants with similar flower heads like dill will turn grey/brown when ripe. They come off easily from the flower heads. I just get a bag and rub the heads and the seeds fall into the bag.
With onion family plants, the pods that develop turn from green to light tan, and the seeds inside turn black. I cut the whole heads of seed pods off into a paper bag. Then I let them dry for a bit more so the pods just crumb away when I separate them.
Hope this helps,
Remy

Thanks Remy. Just what I needed. Now I can clear those spaces for winter stuff. Nancy

You're welcome,
Remy