Cut cucumbers into small cubes. With mushrooms drain off any excess liquid. If they are large, then cut them into small pieces.
Peel potatoes and eggs. Eggs grate on a small grater, potatoes cut into not large cubes. Prunes should be soft, fresh ( pre-soak is not necessary). Prunes cut as little as possible. To collect the salad layers:
1) potatoes+ mayonnaise
4) cheese+ mayonnaise