Your question doesn't indicate where you live or in what USDA Zone you live. There are many shade-tolerant plants that you could grow under your mulberry tree. Do you prefer annuals, perennials, or a mix of the two? You could also use our plant encyclopedia to search for plants that would grow in shade in your specific zone. Go to http://www.bhg.com/gardening/plant-dictionary/ and use the advanced search function to search for plants with shade tolerance, hardy to your zone, and in whatever colors and heights that you prefer.