U.S. government versions of the Great Seal show the constellation of 13 stars in a Hexagram pattern (two triangles intersecting to form a six-Pointed Star). There has been much speculation about the symbolic intent of this hexagram, but it may have been simply a rearrangement of the 13 stars on the first American flag.
– Thirteen Stars Forming a Constellation, GreatSeal.com
The thirteen stars, representing the 13 original states, do indeed form the Star of David (also known as “Solomon’s seal”). Exactly why, I don’t know. In general, though, it’s clear that Franklin and Jefferson had “biblical” motif in mind…
– In G-d We Trust (All Others Pay Cash), Ask the Rabbi, Reb Meir Schuster, Ohr Somayach
The key attention-grabber, the arrangement of the stars in the crest into a “Star of David,” was simply another bit of artistic liberty…So much for commemorating the Jewish people on the nation’s money. It was a widely accepted English heraldic convention of the time that stars had six points, unless specified otherwise, and it was just as natural for an artist to arrange them into a bigger star of six points as for five-pointed stars to be arranged into a bigger five-pointed star, as was done on many American flags of the early 19th century.
– The Arms of the United States: Myths, Mistakes, and Misconceptions, by Joseph McMillan, AmericanHeraldry.org