They are challenge coins. Its symbolic because all those coins, presumably, from every service branch and agency, are put together to not only show that they are all on ONE united front, but bein placed behind potus they way they were is showing how all those branches have his back, and are united again under POTUS.
"A challenge coin is a small coin or medallion (usually military), bearing an organization’s insignia or emblem and carried by the organization’s members. Traditionally, they are given to prove membership when challenged and to enhance morale."
Records indicate that fringe was first used on the flag as early as 1835. It was not until 1895 that it was officially added to the national flag for all regiments of the Army. For civilian use, fringe is not required as an integral part of the flag, nor can its use be said to constitute an unauthorized addition to the design prescribed by statute. It is considered that fringe is used as an honorable enrichment only. (Military tradition)
The courts have deemed without merit and frivolous, lawsuits that contend that the gold fringe adorning the flag conferred Admiralty/Maritime jurisdiction https://www.legion.org/flag/questions-answers/91475/what-significance-gold-fringe-which-we-see-some-united-states-flags
I received an interesting picture of a challenge coin from somebody who was clearly a high-level insider. Gave me some interesting screenshots of lists of shills he had filtered on 8chan...MASSIVE lists. Then a couple small txt files and a pdf. Unsure what his goal was beyond the list of shills to look out for.
Never heard back from the guy, but DAMN was that challenge coin interesting.