One of the longer running open knowledge communities still in existence today is the cannabis community. People are growing their medicine at home. How great is that?

There's a rather vibrant community of DIY cannabis growers on Reddit. Subforums include /r/microgrowery, /r/macrogrowery, /r/autoflowers, and a very niche /r/spacebuckets.

DIY growers cross-bred small lots over years and years, ultimately creating most of the 1000+ strains enjoyed today. A while back, a small group of pot entrepreneurs registered the genetics of these strains in the public domain so that corporations couldn't patent them: https://opencannabisproject.org/