This is a Crab Spider in the family Thomisidae, and this particular species makes its living ambush hunting in flowers.
Ya gotta love his attitude. Once I got closer with my macro lens he hid in the yellow flower stamens, and then came out to protect his turf, as in the photo above, before scuttling off over the edge of the leaf.
Thomisidae do not build webs to trap prey, though all of them produce silk for drop lines and sundry reproductive purposes; this particular species sits on or beside flowers or fruit, where they grab visiting insects. Some species of these amazing animals, such as Misumena vatia, are able to change colour over a period of some days, to match the flower on which they are sitting.
Below is how i first spotted him. Notice the colour difference and subdued lighting before I used the ring flash.