This is a Crab Spider. Many Crab Spiders have the ability to change their color to match white or yellow flowers. This change is not quick, usually taking several days to several weeks. The spider has three color layers in its skin. The middle layer contains a white pigment called guanine. A mixture of yellow pigments can be moved between the top and bottom layers. If all the yellow pigment moves to the bottom, then you only see the while layer. The spider moves just enough yellow to the top layer to let it match the color of the flowers it is hiding on. They do not have the pigments to match blue, red, or purple flowers.