The first online CoP I got involved in was on the forums of the site LDONLINE.org back in oh, 1996 or so. Half a dozen teachers got to know each other answering parent questions and sharing, sharing. We were enough to fend off some serious trolls (tho' I don't know if we could have in this day and age) b/c we'd just start more discussions and their pontifications about Having The Perfect REading Solution drifted to the bottom. The community thrived for several years (though the site folks thought it was a royal technical / monitoring PAIN ;)) ... and hten blew up and died when they changed the format and it was harder to navigate.
Fast forward a decade or so and ... I'm in my little off-the-radar corner helping developmental students ... and I find https://lincs.ed.gov/ . The site is all about "adult ed" and while institutionally I'm not officially "adult ed," there's so much we have in common. I could lurk and learn about things I don't know much about -- a lot! -- and share stuff I am learning.
Yes, I can feel marginalized -- imagine how faculty might just feel about somebody helping the lower-level learners, who isn't faculty adn has a ... special ed background. So... I *ran* towards LINCS where... nobody on the INternet knows I'm a dog! My skills and knowledge speak for themselves... and when there was an opportunity to apply for a project learning about and curating/making OER for adult ed STEM... I did. Then there was a MOOC about *designing* lessons specifically for adult learners including looking at assorted possible profiles of learners to empathize with (including folks with learning disabilities)... so I signed up and did that... and then there were two more projects, one of which is winding up this week, creating/curating math OER for adult ed.
Yes, I do feel like I'm out in the margins in the OER world, too, especially when discussion narrows in on "textbook adoption" and institutional policies... but then I get back to playing with the Open Source geogebra applets https://www.geogebra.org/m/T9jPesSF ... and I submitted a "beta project" -- because it asks "what stage is your project?" and I could say "just barely beginning' -- to the Rebus Community about ... making a full-on interactive basic math program for marginalized math learners.
Another CoP is #mtbos -- the "math twitter blog o sphere." I tripped over it when there was a contest to critique and improve a Khan Academy math lesson... and there is so much sharing there! People send links to files on dropbox, etc. with images, exercises, etc., most w/o any reference to OER or CC licensing.
Time to get back to making OER :)