A lovely white butterfly with black/dark brown markings was feeding on the blossoms of a succulent. I found the ID on Art Shapiro's Butterfly Site - http://butterfly.ucdavis.edu/ - a wonderful place to look at all the many butterflies that grace us with their presence.
The butterfly in my garden was a Pine White, Neophasia menapia. As their name implies, these beauties visit Pine trees, laying their eggs on pine needles. Welcome to my garden, Pine White!