Is it small or the size of a lotus? could it be a rain lily? A picture would help a lot.

It sounds like a rain lily (Cooperia pedunculata). They only bloom after a rainfall. After they flower, they produce small black seeds w/ a paper-like coating that helps them float in the wind. The seeds sprout and create a bulb that stays dormant until the next rainfall causes it to bloom. The white variety seems to be the most common. I've also seen yellow and pink varieties. If you let them flower and go to seed, you can have a nice little grouping in a few years. One of those lovely surprises after a good rain. :-)

Here is a link that might be useful: Hill Country Rain Lily

All my Copper or Rain Lilies are pink and they are bulbs and divide all the time. Sometimes as many as 3 each year. They seem to handle the dry season well but do their best after a rain. Their leaves are like thick blades of monkey grass, but only a few per bulb. The petals are more oval than sword-like. Meden_theshade That Hill Country Rain Lily looks somewhat like mine but the petals don't over lap are more uniform. Nice picture. I was given all my bulbs by a Friend living in Lake Jackson