I’ll add that the inner part of the stem tastes a lot like cucumber. It’s really good when eaten raw by itself. Just grab the leaves and pull them up, it’ll come right out. Wash them really well to avoid (mostly) the risk of some nasty GI parasite and eat the white part. I haven’t tried the pollen or roots yet, but likely will sometime.
I’ll also add that from what I’ve been told by both my parents and grandparents (who lived through it), cattails was one of the primary wild foods for families hit hard in the great depression and left homeless and hungry. I’ve eaten them before and highly recommend them (IMHO the inner stalk is best especially raw).
If you want more information on eating them, here is a link to a video and article on cattails by a gentleman on YouTube who is an authority on wild edible plants. Bon appeteit!