These species are protandrous, meaning the flowers separate the timing of donating pollen (acting as a male) and receiving pollen (acting as a female). Each flower will act as a male, by making pollen available to pollinators, for approximately one day. Then, the flower will act as a female, by making its stigma available to receive pollen, for one day or more.
Below is a flower in the male-phase. If you look closely, you can see that there is pollen available on the anthers, the male organ of the flower. This pollen is available for pollinators to remove.
Claytonia virginica, female-phase flower
As you inspect flowers in the field, you will notice that on one stem, there will usually be one or two flowers in the male-phase, as well as two or more flowers in the female-phase. You might also notice that the male-phase flowers are above the female-phase flowers; this is because they are younger, and flowers open starting at the bottom.