Spinach Salad with Strawberries and Blueberries

1 bag spinach, cleaned, stemmed, torn into bite-sized pieces mix add dress
sliced strawberries
whole blueberries
halved walnuts or pecans  
⅓ c sugar shake
1 t salt
1 t dry mustard
⅓ c white wine vinegar
1 c olive oil
1 T poppy seeds
  1. Mix spinach, strawberries, and blueberries
  2. Add nuts
  3. Just before serving, mix everything else in a covered jar, shake, and dress salad