Cook bacon in a large, deep skillet over medium-high heat, turning occasionally, until evenly browned. Reserve 2 tablespoons bacon drippings. Crumble bacon; set aside.

Meanwhile, place eggs in a saucepan and cover with cold water; bring to a boil. Cover, remove from heat, and let eggs stand in hot water for 10 to 12 minutes. Remove eggs from hot water and cool under cold running water; peel and cut into wedges.

Heat reserved 2 tablespoons drippings in the same skillet; stir in vinegar, water, sugar, and salt. Keep warm.

Wash and remove stems from spinach; dry thoroughly. Tear into pieces in a salad bowl; add warm dressing and toss until coated.

Top salad with mushrooms and bacon; garnish with egg.