World Wide Opportunities on Organic Farms
There are a number of lists for this organization, eg. WWOOF UK , WWOOF independents, which covers a more world wide farm network, and Australia and New Zealand have their own lists. I imagine this would be true of the US though I haven’t visited their farms. Though I do recommend going to ThoughtMaybe.com website where amongst one of their many videos, you will find Digging the Dirt on the Real Farmer John, a wonderful film on the current movement in the US.
Also see Angelics organics, a truly inspiring organisation in the Chicago area. Most people go WWOOFing on weekends , but some places offer long time staying. You typically offer six hours work a day usually with the people who run the place. I once spent a long weekend on an artist’s property, helping him set up an exhibition, so the activity can be very varied. In Ireland I stayed with a Celtic priest and was part of a marriage ceremony that he conducts.