E Pluribus Unum, The Great Seal of the United States

Arms:
Paleways of thirteen pieces, argent and gules; a chief, azure; the escutcheon on the breast of the American eagle displayed proper, holding in his dexter talon an olive branch, and in his sinister a bundle of thirteen arrows, all proper, and in his beak a scroll, inscribed with this motto, E Pluribus Unum.
Crest:
Over the head of the eagle, which appears above the escutcheon, a glory, or, breaking through a cloud, proper, and surrounding thirteen stars, forming a constellation argent, on an azure field."
Motto:
E Pluribus Unum

Front and Reverse

In 1776 Benjamin Franklin, John Adams, and Thomas Jefferson were appointed to design the Great Seal of the newly formed United States.  They created the preliminary design. Two committees and 6 years later the Great Seal was created (1782).

The symbolism in the Great Seal was explained by the designers:
On the front the 13 stripes on the shield represent the original states united. E Pluribus Unum (Out of many, one) refers to this union. The eagle signifies the newly formed union should rely upon itself. The olive branch and arrows of course, denote peace and war. The 13 stars in the constellation at the top indicate the US taking it's place as a sovereign nation.

On the reverse the pyramid signifies strength and duration. The eye and Annuit Coeptis (Providence has favored our undertakings) symbolize providence in favour of the American cause. The date 1776 is obvious. the Latin Novus Ordo Seclorum (A new order of the ages) refers to the newly formed union.

Read transcript from the Papers of the Congressional Congress from 1782. The details of the great seal commence under Thursday, June 20th, 1782.

Note: E Pluribus Unum, although intended to be the national motto, was never technically designated as such.  "In God We Trust" was designated the national motto by an Act of Congress in 1956.

Something else I learned: There is a lot of conspiracy stuff related to the design of the Great Seal of the United States.