Elaborate fountain built in the time of the Gardener Kings (base) and renovated by the Tyrells (elaborate water spouty bit). Even includes a little sitting area for Willas to read important documents or to write letters to Oberyn.
A more recently-made fountain with cleaner stones and elaborate flower arrangements
Marble gazebo grown over with flowering vines for extra privacy and a cyvasse table for Garlan and Willas
Old swing for when the Tyrells were still children and Alerie and Mace would spend afternoons with them.
Seating area for Olenna and Margaery scheming, with cheese for the Queen of Thorns of course.
Potted peach tree, specifically set aside for when Renly visits.
Different variations for outdoor planters
2 variations of flowers in vases
Golden roses for the fields outside of Highgarden. The wildflowers surrounding the shrub is meant as a continuation of the colors of the roses, but without making it a monoculture of nothing but roses.
Concept for a thorny climbing rose.