From the Internet:

Early American settlers, who took note of the large and impressive flower heads, called them “Lamparas de Dios” or “the Lamps of God.”

Yuccas are native to the hot and dry parts of North America, Central America, and the West Indies.

Yucca flowers are oriented downwards during the day. They change position and orient themselves upwards during the night. Flowers release pleasant odor that is especially prominent during the night to attract yucca moths, responsible for the pollination of this plant.

(I did not know this. I will have to go out and check on them at nighttime.)

Yucca flowers are pendulous (bell shaped) and greenish white. They are edible and taste like bitter artichoke. Besides the flowers, fruit, seed and stems can be also used in human diet. The flowers can be eaten raw or lightly sautéed.

They also serve as forage for mule deer, pronghorn antelope, birds and other wildlife species.

The Yucca glauca was adopted as the New Mexico State Flower on March 14, 1927. Yucca is a symbol of sturdiness as well as beauty.

Various indigenous tribes used yucca for the manufacture of sandals, clothes, baskets and mats. Native Americans used yucca in treatment of arthritis, painful joints, inflammation, skin injuries, sprains, and to stop the bleeding. Extract of yucca can be also used in treatment of liver and kidney disorders, hypertension, migraine, wounds and hypercholesterolemia. Latest medical studies suggest that yucca has potential to prevent formation of blood clots (and associated disorders such as stroke and heart attack). 

Yucca can survive up to 1,000 years in the wild.