This grower is fairly sure of this plant identification.
Euphorbia characias (Spurge). This is a shrubby perennial with unusual flowers of deep rich green which are usually cup-shaped and held in large clusters. They are often used as an ornamental accent in both formal and informal gardens.
They are hardy and evergreen. Watch out; they are poisonous and allergenic.
Border, hedging, edging, foliage, ornamental.