Enoki mushrooms are thin and tall Asian mushrooms. I haven’t seen them in neighborhood American grocery stores or organic stores, but they are regular items in Asian grocery stores. They are sold around $1~$2 a package all year round.
Enoki mushrooms have mild flavor, and has significant crunchy texture, which retains well even after stewed. So that they are one of the favorite ingredients of nabe or soup.
When you choose enoki mushrooms, pick the one with the stems are bright white and not watery. When they get old, the color turn grayish, and look soggy. They can be kept in a refrigerator up to a week. The caps and the long stems are edible. Just cut the connected roots part off, and discard. Then the each stems can be separated.
Enoki mushrooms are also great to use in an omelet. Chop them in 1″ length and stir fry them in a pan with butter, before adding them to an omelet.