Never eaten cattails, mostly because the water I frequent doesn't have them. I don't do a lot of foraging, but only eat edible weeds from my garden since I know they're not sprayed with anything and I don't have to work hard to get them. Redroot pigweed, lambsquarters, and purslane, and the occasional dandelion, usually in the early season until the stuff I planted starts producing. Occasionally common mallow comes up in my garden too and you can eat that too, but I don't care for it. I throw it to the chickens. You can plant domesticated cultivars of amaranth, purslane, and quinoa in your garden and let them go to seed and cross pollination will improve the eating quality of the pigweed, purslane, and lambsquarters in your garden if they cross pollinate. If I'm going to have weeds, I'm going to have tasty weeds.