Coin messages on military headstones

[snopes]

Comment: While visiting some cemeteries you may notice that headstones
marking certain graves have coins on them, left by previous visitors to
the grave. These coins have distinct meanings when left on the headstones
of those who gave their life while serving in America's military, & these
meanings vary depending on the denomination of coin.

A coin left on a headstone or at the grave site is meant as a message to
the deceased soldier's family that someone else has visited the grave to
pay respect. Leaving a penny at the grave means simply that you visited.

A nickel indicates that you & the deceased trained at boot camp
together,while a dime means you served with him in some capacity. By
leaving a quarter at the grave, you are telling the family that you were
with the solider when he was killed. According to tradition, the money
left at graves in national cemeteries & state veterans cemeteries is
eventually collected, & the funds are put toward maintaining the cemetery
or paying burial costs for indigent veterans.

In the U.S., this practice became common during the Vietnam war, due to
the political divide in the country over the war; leaving a coin was seen
as a more practical way to communicate that you had visited the grave than
contacting the soldier's family, which could devolve into an uncomfortable
argument over politics relating to the war. Some Vietnam veterans would
leave coins as a "down payment" to buy their fallen comrades a beer or
play a hand of cards when they would finally be reunited.

The tradition of leaving coins on the headstones of military men & women
can be traced to as far back as the Roman Empire.