Cook lima beans according to package directions. Drain. Rinse with cold water; drain again.
In a mixing bowl combine beans, mushrooms, onion, ham, olives, parsley, and pimiento.
For dressing, in a screw-top jar combine vinegar, oil, garlic, sugar, salt, lemon juice and pepper. Cover, shake to combine. Pour over bean mixture. Toss to coat. Cover; chill 3 to 24 hours before serving, stirring once or twice.