Los Angeles, reathdesign.com Nobody does wallpaper — and its associated color- and pattern-mixing — quite like Frances Merrill of Reath Design. Would you like a custom sofa upholstered in seven different shades of chenille? How about a living room featuring four different florals? Or a kitchen with lavender cabinets, checkerboard floors, cabana-stripe skirting, and a terracotta stove? Somehow, in Merrill’s hands, it all works. What is American design to you, and what excites you about it?…