Over the last few years, I have become increasingly interested in the tiny, non-aquatic, annual Crassula species of western North America:
Sand pygmyweed (Crassula connata) - native
Mossy pygmyweed (Crassula tillaea) - non-native
Aussie pygmyweed (Crassula colligata subsp. lamprosperma) - non-native

I am intrigued by how abundant and easy to find these species can be, while in season, and how easily overlooked they can be by folks who don't generally overlook plants - presumably owing to the small stature of these species.

I am starting this project to see if I can increase interest or activity of naturalists in western North America, in searching out these teeny-tiny, short-lived, plants. I think it would be interesting to better document the distribution, and unusual occurrences, of the native C. connata, but also to improve our understanding of the ranges/spread of the two non-native species.

Main project page: https://www.inaturalist.org/projects/wee-crassula-challenge

I'm tagging a number of folks down in the comments, and if you are interested, go out and observe some of these wee Crassula. This is a "traditional project", so you have to join the project, and then you can add an observation to the project when posting/editing an observation.

As I want to see whether a project like this can actually increase observation activity/interest for these easily overlooked species, I've closed the project to observations from past years. Feel free to share this effort with whomever you wish. I would love to get more people out looking for these wee Crassula species.

Hope you're interested... :)

-Glen