BTW - Charity Navigator is one place to check an organization. Organic Consumers Association has a 2-star rating on Charity Navigator. Another similar organization, for example, Center for Science in the Public Interest, has a 4-star.
I also support organizations against Monsanto...just wish they would use emails rather than calls.
However, I get calls from democracy groups for support due signing petitions. As long as I know who is calling, I do not mind as I can block the calls from ringing.