During the Pershing Expedition the US Army wore the Montana Peak Hat, or Smokey the Bear Hat as it is now often known. These hat are still worn by the US Army for training sergeants, or Drill Sergeants. When they arrived in France these were cut down into side caps for ease of carrying and were replaced by a variety of helmets. The Montana Peak Hat was never worn in combat by any US units, sometimes individual soldiers can bee seen with them behind the lines.
US troops were typically given mixtures of US and British or US and French equipment and weapons. Black US Army troops wore US Army uniforms and boots with French web gear, small arms and helmets.
The US Army used the British Mk V* tank, and with the British produced the Mk VIII Liberty tank. The Mk VIII was not used in combat, but was kept in US service until 1932, and not removed from the inventory until 1940. They also used the French FT-17 and brought over 300 back to the US after the war. The US also manufactured them as the M1917 tank.