Lately, Unmanned Aerial Vehicles (UAVs) have evolved considerably, and are proving to be very useful for many important applications in commercial, metropolitan, and military environments. Typically, UAVs require the collaboration with other systems to achieve their mission. Wireless Sensor Networks (WSNs) constitute an example of such systems. In traditional applications, UAVs obtain the required data from specific sensors in a peer-to-peer network. However, this network architecture restricts the scalability and development of the application. This paper proposes a softwarization architecture for UAVs and WSNs collaboration based on the Internet of Things (IoT) model. The higher layers are proposed to be a part of the cloud to take advantage of important and useful cloud services, while UAVs and WSNs are devices that interact with the real world. Our proposed architecture uses a combination of three paradigms which include network softwarization, Software Defined Networks (SDN), and Network Functional Virtualization (NFV). These strategies are associated with decoupling the hardware devices from the control layer that virtualizes the device resources for the higher layers. The architecture is illustrated with an agricultural example of a collaborative system that consists of multiple sensors and UAVs. A prototype system that consists of sensing nodes, UAVs, a WSN controller, a UAV controller, and an orchestration layer was implemented. This implementation provides a proof of our architecture by implementing the layers and components and then testing the system operation.