The common name for Houttuynia cordata in Chinese is Fish Smell Grass, and even in China only people from the southern provinces such Guizhou and Guangxi really appreciate its flavor. One tuber/corm that is ever available in Asian markets is Eleocharis dulcis, or Chinese Water Chestnut. These are very easy to grow in a shallow pond. Another water vegetable that is only available in the fall is Trapa bicornis. What is sold is a menacing black seed about 1-2" across with two horns. The plant itself grows wild in lakes in central and south China. Seed collecting were traditionally done by young girls in small boats and the whole experience has been romantized in traditional Chinese literature. When I first came to the U.S. in 1990, I could not find celtuce. They started to become available only four or five years ago. Also becoming available is young flower stalks of garlic, which was one of my favorite vegetables. Daxin Liu Fragrant Hill Design http://www.fragranthill.com/