Found this interesting page on how to harvest cattails and recipes:
Cattails (Typha species)
The cattail is one of the most important and common wild foods, with a variety of uses at different times of the year. Whatever you call it, a stand of cattails is as close as you'll get to finding a wild supermarket.
One of the new shoots broke off yesterday during transplanting and it really does taste good. I think we'll expand our garden cattail pond or have several. They'll make a nice fence, provide shade and a wind break and grow really fast.