I found this on the web site USFlag.org.
From the book "Our Flag" published in 1989 by the House of Representatives...
"On July 4, 1776, the Continental Congress passed a resolution authorizing a committee to devise a seal for the United States of America. This mission, designed to reflect the Founding Fathers' beliefs, values, and sovereignty of the new Nation, did not become a reality until June 20, 1782. In heraldic devices, such as seals, each element has a specific meaning. Even colors have specific meanings. The colors red, white, and blue did not have meanings for The Stars and Stripes when it was adopted in 1777. However, the colors in the Great Seal did have specific meanings. Charles Thompson, Secretary of the Continental Congress, reporting to Congress on the Seal, stated:
"The colors of the pales (the vertical stripes) are those used in the flag of the United States of America; White signifies purity and innocence, Red, hardiness & valour, and Blue, the color of the Chief (the broad band above the stripes) signifies vigilance, perseverance & justice."
Also this from a book about the flag published in 1977 by the House of Representatives...
"The star is a symbol of the heavens and the divine goal to which man has aspired from time immemorial; the stripe is symbolic of the rays of light emanating from the sun."
The quote below concerning gold fringe on the Flag is from the book "So Proudly We Hail, The History of the United States Flag" Smithsonian Institute Press 1981, by Wiliam R. Furlong and Byron McCandless. "The placing of a fringe on Our Flag is optional with the person of organization, and no Act of Congress or Executive Order either prohibits the practice, according to the Institute of Hearaldry. Fringe is used on indoor flags only, as fringe on flags on outdoor flags would deteriorate rapidly. The fringe on a Flag is considered and 'honorable enrichment only', and its official use by the US Army dates from 1895.. A 1925 Attorney General's Opinion states: 'the fringe does not appear to be regarded as an integral part of the Flag, and its presence cannot be said to constitute an unauthorized addition to the design prescribed by statute. An external fringe is to be distinguished from letters, words, or emblematic designs printed or superimposed upon the body of the flag itself. Under law, such additions might be open to objection as unauthorized; but the same is not necessarily true of the fringe.'"
The gold trim is generally used on ceremonial indoor flags that are used for special services and is believed to have been first used in a military setting. It has no specific significance that I have ever run across, and its (gold trim) use is in compliance with applicable flag codes and laws.
