Chaparral yucca, our Lord's candle, Spanish bayonet, Quixote yucca or foothill yucca

"Dense, evergreen cluster of rigid, gray-green basal leaves to 2’ long, often shorter. Forms a tight basal rosette 4-5’ in diameter. Leaf tips are needle sharp.
Single flower stalk 6-14’ tall, develops on mature plants from mid-spring to summer, covered in showy, creamy white flowers.
Plants die after blooming but young plants commonly develop from offsets." Source: nativeson.com

This yucca was about ten feet tall. Best not touch, because they're sticky.