Who would think humble romaine lettuces could form the centerpiece of a decorative patio garden bed? To create this design, purchase an inexpensive, vertical wood trellis, cut off the two legs, then paint it an inviting color, such as this soft purple. After laying it on the prepared soil, plant a single lettuce in each square. As the lettuce grows, continually harvest a few outer leaves from each plant to maintain the design. Oregano, cilantro, mustard, flax and nonedible hens-and-chicks frame the vignette.