1. Pick a mushroom (from the wild or the supermarket) and break off the stem.
2. Put your mushroom, spore side down, on a piece of white paper (or a 50/50 split of of dark paper and white paper to check subtleties in the color).
3. Put a glass over the mushroom and wait 24 hours.
The next day you should have something that looks like the picture above. Spore prints can be used as one factor in identification. The above print is from a specimen of Agaricus bernardii that I found growing in the neighborhood and had identified by mycologist Bob Cummings at Machine Project’s Fungi Fest back in January. Agaricus bernardii is a common mushroom found growing in weedy lawns and is a choice edible according to some. My identification skills are not up to eating parkway mushrooms yet.
Speaking of Fungi Fests, the Los Angeles Mycological Society is putting on the 26th Annual Los Angeles Wild Mushroom Fair this Sunday, February 14, 2010 from 10 AM – 4 PM at Ayres Hall at the Los Angeles County Arboretum & Botanic Garden. Mushroom celebrity Paul Stamets will be speaking at 2 p.m. More info on the website of the Los Angeles Mycological Society.
Not in LA? Spend some time reading Mykoweb.com, and excellent and entertaining resource published by Michael Wood, a past president of the Mycological Society of San Francisco.