Well, one of his books, anyway.
Identifying and Harvesting Edible and Medicinal Plants in the Wild (and Not So Wild) Places, written with Evelyn Dean illustrating.
It has to be one of the most clearly written, entertaining, practically formatted books I have found. He takes you through the seasons and the plants you will find for harvest during each, gives you tips on observing other plants, at other than peak times, great information on exactly how good foraged foods are, tells you if there are poisonous look-alikes and gives advanced identifying information. The illustrations are detailed, and ID helps are clearly noted.
For a beginning forager or wildcrafter, (of which we seem to have a few here), I recommend it, along with the Peterson Field Guides my copy of "Eastern/Central Medicinal Plants and Herbs" by Foster and Duke is about beaten to a pulp. Lots o' mileage on the poor thing.
The copy of Wildman's book I have might be a bit large for actually carrying with you in the field, but perhaps not. It's not heavy, and I can see it slipping into a backpack or bicycle basket rather nicely.
At the least, though, one can use it to get an idea of what they can look for before going out, what they might be interested in gathering, etc. He also gives information of equipment and knowledge to have with you, for identification and safe out-n-abouts. I would almost call it a primer, but even well experienced folk will appreciate it.
It also is just great to sit down with a hot cuppa and read. It's like Henrietta's site: you get into it, and you don't want to leave.