Many field guides will list the scientific name of shaggy parasol as Lepiota rachodes, but again, molecular techniques have split the traditional genus Lepiota into a number of genera. Michael Kuo of MushroomExpert.com explains the changes (and offers a few opinions) in two online articles: Lepiota and Satellite Genera and Taxonomy in Transition: The Lepiotoid Clade.
Shaggy parasol is distributed throughout much of North America and Europe. It is edible, but as silvercreek_garden notes, some people have allergic reactions to it. I suppose I should add: be absolutely certain about the identity of any mushroom before ingesting it; though difficult to mistake for anything else, there are a few lookalikes for shaggy parasol that an untrained observer might err on (including toxic amanitas). Mykoweb has a good description of Macrolepiota rachodes with comments on its lookalikes (and there is a separate page with recipes).
Botany resource link: “The Botanist Effect” (subscription required if you want to read more than the abstract), a paper in the November 2006 issue of the Journal of Biogeography by Moerman and Esterbrook. The subtitle provides a good summary: “Counties with maximal species richness tend to be home to universities and botanists”.