Pittsburgh is a great place to be a veggie with all the grocery options available in one city.  Here's a description of all the best places to score produce, dry goods, and specialty items.

CO-OPs:

East End Food Co-op

Farmers Markets:

CityParks Farmers Markets [7 locations!]

Farmers@Firehouse

Other Info Sources:

PASA Markets Guide

LocalHarvest Markets Guide

Farms That Deliver Food By Subscription

Kretschmann Organic Farm

Chain Grocery Stores:

Giant Eagle Market District

Trader Joes

Whole Foods