I don't know about Yunnan, but here are some Sichuan adresses I got out of a magazine. They might be able to tell you about Yunnan organic farms. I copy from the magazine:
Wenjingyuan Organic Farm, Qiquan Town of Chongzhou City, (028)8238-0478,400-612-5700
Jiutian Family Farm, Lianyu Village, Jinqiao Town, Shuangliu County, (028)8572-3085, 13808002921
Sunshine Earth Organic Farm, Xingyi Town, Xinjin County, Chengdu
Anlong Village, Ande Town, Pi County, 15828581360 (in the village, the Gao farming family is supposed to be the representive of local organic farming).
Chengdu Sunyuki Organic food Co., has product bases in Dujiangyan, Shuangliu, Pengzhou, Jintang and Xichang, 400-6828-300.
Hope this helps. If you find anything about Yunnan, let us all know!
