It depends on what you use the garden for. From the size it is not really somewhere for the children to run around in so consider making a gravel garden or raised beds.

Posted By: RobinBSedum or cammomile lawn? But not ideal for playing on. When my child was small I wanted to do our back yard in that rubber stuff they put down in children's playgrounds so we could just bounce about.

Yup, good ideas. I had a chamomile lawn at a previous house. It works but can get a bit unruly. Nowadays we grow it as a decorative crop, cos SWMBO likes chamomile tea. Not sure how well sedum likes being walked or played upon, but it generally grows well. Another possibility is pennyroyal and there are various others; the best choice will depend a lot on what the soil is like and how moist it is. I'm planning on using Corsican Thyme for one smallish area. Searching for 'alternative lawn' gives a lot of lists.