Food co-ops are supermarkets owned and ran by members, usually with a focus on providing natural, organic food and produce from local sources whenever possible.
1600 E Madison St and Pine St, on Capitol Hill. On the web at centralcoop.coop.
Certified-organic market, with a large selection of organic produce, meat, fish, and poultry, grocery items, natural health product and a kitchen deli and espresso bar. Owner investment is $60, although non-members can shop at any time. Owners get additional discounts, such as 5% off on Member Appreciation Day--second Wednesdays--and monthly discounts for an extra 10%-off one purchase per month.
The "largest natural food cooperative in the United States", PCC locations are quite large and offer pretty much the whole array of natural food products and produce. Membership fee is $60, non-members can shop too, with members getting additional discounts and member days twice a month on the 15th and 16th.