New green leaf stalks can be split out and eaten like celery. A little snack. Reminds me of cucumber.
Find a male flower spike which has not yet shed its pollen. Look for bright yellow tips above the green cattail. The flowers in the area where we gathered pollen were at their best when small flies could be seen clinging to the male flowers. Carefully bend the flower into a collecting sack, and then tap it to release the pollen. Its not unusual to get a tablespoon or more from a single flower. Be careful not to break the stem. If you do, the pollen explodes off the tip, and the female flowers will fail to develop seed.
The male flower's edible pollen was used like flour. Immature flowers (male and female) were eaten while still sheathed. The bloom stalk can be used as a fire stick when thoroughly dry. The same flower later produces cattail fluff, versatile as insulation, tinder, cradle board padding, and wound dressing. The root stalks are rich in starch, and can be processed as a food.