I happened to notice this volunteer growing in the backyard in the soil under the Bird of Paradise. My first thought was that it might be an onion, but Early Onion has a stripe down the middle of the petal. The next close-ish plant I saw was a Death Camas, but the green anthers persuaded me that it was not. It appears to be a Common Muilla, Muilla maritama, a close relative of the bright yellow Golden Star, another native plant that flowers in a globe.