What is a purple lemon-scented shrub?

When I was little I remember this plant my mom had in her garden. I'd like to plant it in my own garden now but I have no idea what it was. It had teeny little purplish flowers but most of it was green little leafy things. It didn't stand upright, it was more like a spreading shrubby herb. Any suggestions so I can bing-image would be great, thank you!