These are grown on rice straw and are not yet widely available fresh even in California. They are, however, available canned in stores catering to Asian communities. Caution: Mistaking the almost identical but highly toxic death cap (Amanita phalloides) for straw mushrooms has resulted in death and/or need for liver transplants among Asian immigrants to the US and Australia.
Straw mushrooms are canned in two forms: egg shaped with the cap and stem still completely encapsulated by a shroud called the volva, or partially opened with a conical cap on a short thick stem. These are called "unpeeled" and "peeled" on the can but the "peeled" is just a more mature form of the "unpeeled". The unpeeled can be much larger than the one in the photo. They are also available dried (right in photo) but not so commonly. Straw Mushrooms are very important in Southeast Asian cuisines, particularly Thai. In Vietnam they may be found growing wild on old termite mounds. These are much stronger in flavor than cultivated and fetch a much higher price.
More on Mushrooms.
Dried straw mushrooms aren't common, but are available in larger Asian markets. They are somewhat different (a little more intense) in flavor, but still recognizable as straw mushrooms. Soak them in hot water for 1/2 hour before cooking with them, and do use the soaking liquid in the recipe, it is quite good.
fu_strawz 081026 - www.clovegarden.com