This time of year, Cat tails fuzz and the fuzz from some awful alien invader grass are plentiful. If anything, the cat tail fuzz burns too fast.
Birch bark is very rare. Scouts needed to "spot" it are left with plantings in house landscaping, where Black Birch (AKA "river birch") is used for its resistance to the borer. Our long warm spell until Fall, 2013 was wonderful for the borers.
There have been user reports of Wetfire tinder that would not light when exposed to open flames for extended periods. Others claim it lasts for several years if kept in a plastic bag.
Codger's birch bark, like cotton balls, lasts for centuries if kept dry, as you would keep tinder given a choice.