Heraldry and Coats of Arms
Medieval heraldry and the use of heraldic symbols on shields has remained a hot topic among amateurs interested in "medievalism," as well as those strange creatures who still believe feudal titles really indicate their bearers' superiority. Unfortunately, as far as I can tell, there are no scholarly web sites which provide samples of heraldic coats of arms from Chaucer's time, but you will find a good page of examples in the hard copy of the Encyclopedia Britannica. Fortunately for us, the state flag of Maryland bears the arms of the Calvert and Crossland families. Maryland was founded by Cecil Calvert, the second Lord Baltimore, who received the original royal land patent on the Chesapeake Bay region from Charles I in 1634. In it, you can see the abstract patterns and symbolic icons used to represent that family's lineage. It is the medieval equivalent of a DNA test.
The black and yellow pattern comes from the Calvert family arms (Cecil's dad's folks) and the red and white pattern comes from the Crossland family arms (Cecil's mom's folks). The "cross" pattern in the Crossland family's arms might have been considered "canting arms" in that the image puns on the family's name.