The Biodynamic Farming and Gardening Association (BDA)
https://www.biodynamics.com/
An association of individuals and organizations in North America who are committed to the transformation of the whole food system, from farm to table, and who draw inspiration from the spiritual-scientific insights of Rudolf Steiner.  Subscriptions are available for their quarterly magazine “Biodynamics”, and they are a wonderful resource for reading materials, calendars and guides.

The Josephine Porter Institute for Applied Bio-Dynamics, Inc.
http://www.jpibiodynamics.org/
Supporting gardeners and farmers in their practice of biodynamics since 1985.  JPI provides Biodynamic preparations, educational workshops, books, research, and e-news updates.  JPI publishes Applied Biodynamics quarterly. 

Demeter International (DI)
http://www.demeter.net/
Demeter is the only ecological association that has built up a network of individual certification organizations world-wide.  Presently Demeter International has 16 members from Demeter organizations in Europe, America, Africa and New Zealand, and represents around 4,200 Demeter producers in 43 countries.

Biodynamic Association of Northern California (BDANC)
http://www.bdanc.org/
A member organization that promotes the biodynamic approach to farming and gardening.  This group meets quarterly, publishes a newsletter, and shares insight and experience with each other including resources for making and learning about the preparations.

Turtle Tree Seed
http://www.turtletreeseed.org
518.329.3038 A small non-profit seed company that sells 100% open-pollinated vegetable, herb and flower seeds via an on-line catalog. Organic and Biodynamic, grown in their own seed garden and by other farmers and gardeners, all Turtle Tree seed is non-GMO, non-hybrid, and grown without chemical inputs.