Place the eggs in a small saucepan and cover with just enough cold water to submerge the eggs. Place the pan on the stove and turn the heat to high. As soon as the water begins to boil, turn off the heat and place the lid on the pan. Set a timer for 6 minutes. Once six minutes is up, immediately plunge the eggs in a bowl of icy water with lots of ice. Let the eggs cool down completely, which will take at least 5 minutes. Finally, tap the eggs gently on the countertop all over then peel back the shell. Rinse off the eggs to remove any bits of leftover shell, then chop them and set aside.
Place the spinach, sliced mushrooms and chopped eggs in a large mixing bowl.