There is a cause of action that could, potentially, help you although it is by no means guaranteed.
The cause of action is known as "nuisance" and it is really judged by a reasonableness standard. So, for instance, if you bought a home on the golf course and then complained about the noise of the golfers or that a golf ball hit your house occasionally you likely wouldn't succeed. Under your facts, however, it may be different, particularly if they started this after you bought your house and there really is no reason that they couldn't run the sprinklers a little later.
As to the furniture being wet, that's a little harder to win on since obviously they have to water their grass but at the same time there would have to be a limit on how much water they could direct into your yard.
What I'd suggest you do is visit with a local lawyer who does civil litigation (you can find one at www.lawyers.com) and ask them to write a cease and desist letter or a demand letter asking the golf course to change the timers or advising that you will have to file suit.
You wouldn't be able to make them give you your money back on the lot, but the measure of damages is the amount that their actions decrease the value of the property or, alternatively, you may be able to get a judge to order them to change the timing, direction of the spray, etc.
When you go to see the lawyer bring your paperwork from the purchase of the house, any video or audio you can shoot that shows what's happening, a map or something showing how your lot is placed in relation to the course (you can print it off of Google Earth/Maps), etc.