Answer to Big Question I Have Every Memorial Day

According to a U.S. Army Facebook page:

A coin left on a headstone lets the deceased soldier’s family know that somebody stopped by to pay their respect. Leaving a penny means you visited.

A nickel means that you and the deceased soldier trained at boot camp together. If you served with the soldier, you leave a dime. A quarter is very significant because it means that you were there when that soldier was killed.