In 2004, the U.S. Postal Service issued a 37-cent Love stamp that featured two candy hearts. Boxes of the popular treats are typically exchanged on Valentine’s Day. In fact, the tradition has been around for longer than you might think.

In 2010, Louise McCready of Bon Appetit magazine chronicled the history of Sweethearts Conversation Hearts, which the New England Confectionery Company—known by most as NECCO—began selling in the 1800s:

Originally called “motto hearts,” their precursor was a trendy fortune cookie-like treat sold during the Civil War called a “cockle,” which had printed phrases rolled up inside its scallop-shaped shell. Printing words directly on the candy was the bright idea of Daniel Chase, the brother of NECCO’s founder. He also invented the machine that both pressed red vegetable coloring on the candy dough and cut the shapes.

Over the years, the messages on the hearts have evolved—but the classics remain:

Many of the original sayings, like “Be Good,” “Be True,” and “Kiss Me,” are still printed, but NECCO began to update its lexicon in the late 90’s with hearts that said “Call Me,” “Fax Me,” and “Email Me.” Last year’s new phrases were all food related, from “Recipe 4 Love,” to “Top Chef.” And while it used to be impossible to find the candy hearts during any other time of the year, in March of 2009 NECCO produced Twilight-themed candy hearts, with sayings like “I heart EC,” “Lion and Lamb,” “Bite Me,” “Dazzle” and “Live 4 Ever.”

How popular are Sweethearts Conversation Hearts? According to McCready, about 100,000 pounds of them are sold every day between January 1 and Valentine’s Day.