For your favorite palynologist (or environmental allergy sufferer):

pollen amigurumi. She includes grass, oak, and birch, but a person could also do pine (make big flaps, kind of like Mickey Mouse ears, and attach them to the grain) or my personal un-favorite, ragweed (it would need to be spiky...you'd have to crochet a whole bunch of little cones and sew them on).

I like how people are coming up with these geeky, science-themed patterns.