You can't beat candytuft (Iberis) for bringing you more bang for your gardening buck.
It is an evergreen perennial that chugs along in the garden all year, but really shines in the spring. Just look at it!
It is low growing, perfect for the front of beds, or you could even use it as a ground cover, since it spreads so easily. When it is not blooming, it stays low and mounded with deep green, needle like leaves.