In a sauce pan, boil the eggs in water until cooked through, about 5-7 minutes. Let the eggs rest until cooled enough to peel. Peel eggs and then slice into thin pieces. Set aside. In a saute pan, place the strips of bacon and saute until crispy and browned. Once the bacon is crispy, pour all of the bacon grease out of the pan except keep 3 tablespoons of the fat in the pan. Slice the onions and mushrooms and place in the bacon fat that has been brought back up to medium heat. Let them saute in the grease until tender and soft. Season the vegetables with salt and pepper. Remove the onions and mushrooms and place in a bowl until ready to serve. To the same saute pan, add the olive oil, red wine vinegar, sugar and dijon mustard and bring to a simmer for 1-2 minutes, or until the sugar is dissolved. in a large salad bowl, place the baby spinach, cooked onions and mushrooms, sliced eggs and drizzle with the cooked dressing. Toss the salad and serve warm.