Place cauliflower in a large saucepan and cover with water. Bring to a boil and cook until just fork tender, about 10 minutes. Drain and cool slightly.
In a large bowl whisk together the mayonnaise, mustard, salt, and pepper. Add the cauliflower, eggs, onion, peas, dill pickles, and bacon to the dressing and stir until well coated. Cover and refrigerate for 2 to 24 hours. The longer the cauliflower salad chills, the better the flavor.