Wild Strawberries are a must-have for every native plant garden.  They grow in pretty much all conditions and spread nicely on their own with runners.  They are great for filling in blank spaces instead of using mulch.
When I was growing up, we had lots of native plants like violets and wild strawberries mixed in with our turf lawn.  I always loved searching for the tiny red berries and seeing little butterflies flitting around the little white flowers.  Wild strawberries are mowable and and easy addition if you are trying to diversify your lawn.