The answer is "all over the world" and from different parts of the world for different crops. I've gathered some interesting facts that provide a good overview about these crops. However, keep in mind that these are not absolute in that data varies from one report to another.

Organic Cotton

The Organic Cotton Farm and Fiber Report 2008 released by the Organic Exchange reports that 22 countries grow organic cotton. Organic cotton accounts for approximately 0.6% of all cotton in the world.

India took over Turkey's long-standing position as the leader in organic cotton production, accounting for about half of the world's organic cotton production. Other leading organic cotton producers, according to rank, were Syria, Turkey, China, Tanzania, United States, Uganda, Peru, Egypt and Burkina Faso.

According to a report from the U.S. based Organic Trade Association, U.S. grown organic cotton is approximately 2.1% of global organic cotton. Most was grown in Texas, with limited acreage in California, New Mexico and Missouri.

Although small, organic cotton production has been increasing at rapid rates over the last several years along with demand. Yet, obviously, we still have a long way to go to make the environmental changes that are needed to support a sustainable world.

Bamboo

Bamboo is able to adapt to a wide variety of ecosystems and climatic conditions. Bamboo is grown in numerous countries in Asia, Africa, and Latin America and can grow in at least 70% of the world. There are over 90 genera of bamboo with about 1,200 species globally.

Combining information from several reports, China is the largest bamboo planting country in the world (the majority of the crop is located in south China). There are over 400 varieties in China and China accounts for 25 percent of the world's total area of bamboo. Other top bamboo producing countries are India and Brazil.

Hemp

Hemp is among the oldest industries on the planet, dating back more than 10,000 years. The Columbia History of the World states that the oldest relic of human industry is a bit of hemp fabric dating back to approximately 8,000 BC.

Currently, more than 30 nations grow industrial hemp as an agricultural commodity. About 14 of those sell part of their production on the world market. The U.S. is the only industrialized nation in the world that does not recognize the value of industrial hemp and permit its production.

According to the Hemp Industries Association  China is the largest exporter of hemp textiles. Romania is the largest commercial producer of hemp in Europe. It is exported to Western Europe and the U.S. Hungary is one of the biggest exporters of hemp cordage, rugs and fabric to the U.S. They also export hemp seed, paper and fiberboard. France has never prohibited hemp and is a source of hemp seed for other countries including high quality hemp oil to the U.S.

Interestingly, Poland has demonstrated the benefits of using hemp to cleanse soils contaminated by heavy metals. And Russia maintains the largest hemp germplasm collection in the world at the N.I. Vavilov Scientific Research Institute of Plant Industry (VIR) in St. Petersburg. Turkey has grown hemp for 2,800 years for rope, caulking, birdseed, paper and fuel.

Source: Yes, It's Organic