I have a couple of bushes at the side of my small front lawn. I keep trying things to fill the gap, but it usually ends up a mess, like this:

http://tinypic.com/view.php?pic=1058hsw&s=2

It never gets full sun, so will need plants that are happy to be in the shade, low maintenance and non-invasive of the lawn.

Try bulbs for spring - bluebells will like the shade and I'm sure other bulbs will also cope (tulips / daffodils etc).