Most dryers can't be pushed up against the wall due to the dryer vent so why not build a shelf to cover the gap. Not only does it add more storage but it also keeps items from falling behind the washer and dryer
Ideas for Hidden Laundry Spaces. Links to blog with several different ideas pictured featuring clever ideas to conceal a washer & dryer. Disguise washer & dryer as furniture or hide behind cabinet doors.