I'm a couple days late, but it's a brilliant idea and this is the first I've heard about it. Clearly, I should read Carol every day.
What have I got?
Some of the usual suspects for this time of year.
Nearby...an ipheion (sp?) just flowered.
Not a day goes by without (at least) dozens of Abutilon flowers. Abuliton? I'm always screwing that up.
Same thing with the trailing lantana and cuphea.
Erica (heath) blooms for several months starting now.
The sedum flowers come and go all year.
Does something count if it's only in bud? Because I've got Cotyledon macrantha (Pig's Ear) and Hardenbergia violacea 'Happy Wanderer' coming on board.
Then there are a number of things that will be much more florific in another month or two: Tiarella, Cotula, sad-looking Crocosmia.
But most of my garden is very young. Come back in a few years for the major flowering. As it is, I'm lucky to a have a one or two flowers on most of my plants.
Ribes sanguineum 'Inverness White'
Arctostaphylos bakeri 'Louis Edmunds'
Arctostaphylos pajaroensis (Pajaro Manzinita)
Vaccinium ovatum (Evergreen Huckleberry, Box Blueberry)
Asarum caudatum. This flower is hidden under the foliage, close to the ground. It might not count for our purposes. Regardless, it's a cool-looking flower and I'm sorry this picture's blurry. I'll try to get a better one later.