Yes, it's a caper flower. And yes, it has fallen very low. In fact this plant, its flowers and fruit, not lift a foot off the ground.
It is a wild plant that can be found in several areas of the Mediterranean. One is to the southeast of the Iberian Peninsula, where it is the Region of Murcia. For this plant, you can eat the leaves, stems, their buds; fruit. It is usually done in pickle, and usually accompany salads, pasta, and fish.
If you want to find more info, here in wikipedia.