Love most of this - the lavender, the olive trees, the cupressus - Pinus pinea (stone pine) which gives pine nuts would be a good candidate as its umbrella shape is very structural. Lots of gravel toning in with the stone of the house - perfect.
Euphorbia polychroma: An undemanding perennial, Euphorbia polychroma offers a pleasing contrast of colors on a neat, almost architectural form. It grows to about 15in and produces a splendid show in May from bright yellow bracts. Their color is long lasting, but changes to rose-bronze as they age above the green foliage. A sensational ground cover plant or accent in a sunny garden. Quite tolerant of hot, dry conditions (but not the heat and humidity of the South).