An open-and-shut case

Here's an odd plant in the garden.  An annual, it seems to have adapted to heat by closing its flowers during the daytime.  In the early morning and evening they are open, making a fine display when massed, but by 11:00 they are all closed up.  When open the flowers are about an inch in diameter, maybe a bit bigger, and the pattern in the middle is a chocolate colour.  I must look up their name, because I have forgotten.

P.S. They are Madia elegans, a hardy annual, native of California.