Chicken gizzards

While many people may recoil at the thought of eating bird stomachs, gizzards are actually a popular food item around the world. Gizzards may be poached, boiled, ground, or even deep fried. These giblets are often used to make a stock or broth for dressings and soups. The gizzards alone can also be added to soup stocks for additional flavor. Gizzards are definitely chewy, since they are primarily a membrane more than a muscle.

http://www.wisegeek.com/what-are-gizzards.htm
http://www.saddogsushi.com/pictures/chicken_gizzard.jpg