This may prove a problem for some locations, since you would likely have to put the valves at the highest point in the yard. The control valves may be manually operated or they can be remotely controlled. Manual control is simple, the valve has a handle you use to turn it on. Remote control valves are either electric or hydraulic, but almost everyone uses electric knowdays. Anti-siphon, globe, and angle valves are all available as automatic valves.
Valves come in both brass and plastic models.
Most used today are plastic, but brass is not at all out of the picture. There is no doubt that a brass valve will last longer if installed in the sunlight. From an operational point of view both are reliable, especially for automatic systems. For manual valves my experience is that brass will last much longer. If you use plastic valves above ground you may wish to consider building a cover for them to protect them from sunlight, which can destroy the plastic over time.