Combine sour cream and Ranch Buttermild Dressing mix. Set aside. Combine spinach and lettuce. Place half in large bowl. ( I use a trifle bowl) Spread half of the dressing over green. Then layer in order, egg slices, thawed and drained peas, onion, bacon and remaining salad greens. Spread tthe rest of the dressing over top, sealing well. Refrigerate overnight.