You don't actually gnaw on the cattails, you either dig up the root and prepare it like a potato, or collect the pollen from the 'shoot' at the end of the stalk, and use it like corn flour (cattail is a close cousin to corn) Baby cattails can be eaten like a green. I've done all three. It's a lot of dirty work to get at the root, but that's the best. It's really hard to get enough pollen to use.
Gardoni (commonly referred to as 'burdock') is EXCELLENT! You eat the stems from baby plants. You have to 'defuzz' them with a 3m-pad like sink scrubbie, but it's pretty easy. Boil them up like asparagus (that's what it tastes exactly like) and eat them with a little butter &vinegar, or dip them in your favorite batter, and deep fry them. The other common way is to slice 'em thin (like salad or stuffing celery), mix it with egg, a little flour, and some garlic &onion to your taste. Fry it like a pancake. Serve on a bun or toast. Gardoni sandwich! (an Italian favorite)
These are some of what I like to eat from the wild (along with sorrel......looks like clover, but on long fuzzy stems, with tiiny yellow flowers......it's lightly sour, and resembles lemons in the mouth). Great on salads. Also, Dandelion greens (baby) are great used like spinach - raw or boiled.