Very small decorative elements of terrain less than 2" across at their widest point, such as a stack of barrels or a roadside shrine, are called 'battlefield decorations'. Such small features can be added to the battlefield in the same way as terrain and in the same quantities. In addition, some scenarios might specify that a number of battlefield decorations be included as objectives or as part of the narrative element of the scenario.
Due to their small size, battlefield decorations rarely interfere with a battle. They are ignored for the purposes of both movement and combat, as if they were not there. Should the presence of such a battlefield decoration ever interfere with the positioning of units, simply make note of its position and move it aside, replacing it when it is convenient to do so. However, they may obscure a line of sight.