A couple of heads of bibb lettuce.
bibb lettuce definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a type of butterhead lettuce, formed in loose heads of very crisp, dark-green leaves
Origin: after Jack Bibb (1789-1884), Kentucky horticulturist who developed it
bibb lettuce definition by American Heritage Dictionary
A kind of lettuce forming a small, loose head and having tender, dark green leaves.
Origin: After Jack Bibb, 19th-century American vegetable grower.