Need full sun garden idea

My mother has a large area in her front yard that has one ornamental pear tree out in the middle of nothing. I want to create a circular garden for her that will contain full sun plants that require little work for her. I will put Knock Out Roses in the bed for sure. I think the area that is empty is 50 ft x 50. It isn't a place where she would sit so a bench area isn't a good suggestion. A birdbath would be, but I need more shrubs, lillies, and limited perennials. Open to suggestions for a 15x20 ft area or less.