Antique WW1 Trench Art Officers Cap. 
French or French Belgium. 
With engraving: Ypres, Poperinghe, Souvernir de  La Guerre 1914-15-16

Interesting because it only mentions 3 years of WW1 so probably made in 1916
Also Ypres and the village of Poperinghe is interesting:

On the 19 October 1914, a savage and bitter battle for the strategic town of Ypres, in western Belgium, was taking place. On October 19 the Germans opened their Flanders offensive and the Allies resisted — attacking when and where they could. Ypres was so important because it was the last geographical object protecting the Allied ports at Calais and Boulogne-sur-Mer. The loss of these ports would have denied the shortest logistical supply route to Allied forces on the Front. For the German Army, Ypres was also vital. The collapse of its Ypres front would allow the Allied armies access to the flat and relatively traversable terrain of Flanders. Beyond the Ypres position, the Germans had no significant defensive barrier to protect the massive rail network axis, vital to German strategic and operational mobility in Belgium and the entire northern flank of their front. Such a collapse would also allow the Allies to get to the German-held Belgian ports. Also called the First Battle of Flanders, the Battle of Ypres, along with the Battle of the Somme, will forever encapsulate the futilities of the Great War. Soldiers lived in bleak trench conditions among mud, lice rats and disease and under relentless attack from gas and shells.

The town of Poperinghe (now Poperinge) was of great importance during the First World War because, although occasionally bombed or bombarded at long range, it was the nearest place to Ypres (now Ieper) which was both considerable in size and reasonably safe.
During the First World War Poperinghe was the centre of a large concentration of troops, and there were many camps in the countryside around it. There was generally at least one Division billeted in the town, and it was described in a very early battlefield guide as "a [wartime] centre for recreation, for shopping and for rest". The population before the War was about 12,000, but in 1917 there were as many as 250,000 soldiers billeted in the area. Starting in the town centre, the imposing Town Hall, built in 1911, can be found on the main square. It was used as a Divisional Headquarters during the War.

This cap, which is either a ash tray or pin dish or tobacco tray was probably sold in Poperinghe as a "souvenir de la Guerre".
Good condition. Solidly made. Diameter 9.5 cm.
Please check photo's.