What can I do to get rid of snakes in my yard?

I'm a herpetology major. Two things:
1) If you could describe the snakes, I might be able to tell you if you should be worried. If you are in an Urban area, it is unlikely they are dangerous at all. Especially if they are small.
2) Moth balls *can* work. Research has shown that the "snake repellent" doesn't work as well as the moth balls. The best results we have found for snake exclusion is to lay down a layer of lava rocks around the perimeter of the region where you want to exclude them from (remember, you could trap them *in* too). The lava rocks are very uncomfortable for the snakes to crawl over and they won't harm your dog, unlike the moth balls.

Moth balls are supposed to work. But I have read that if you put them around your yard leave an area open with out moth balls otherwise if a snake gets in it won't get out because it will try to avoid the moth balls, thus stuck in your yard.

Also, check out your local department of natural resources web page for info on the type of snake you are seeing. Some snakes are actually good, and not agressive at all. I know this helped me with my fear of snakes. If you don't already know about the type you are seeing, some information can be really helpful.

I know moth balls work! We put them around our lake lot every year, except this year because we didn't have time to go out there, except to mow & this is the first year we have seen one on our property. Found a big one in the shed!

Moth balls is the simplest remedy. It really works, I have a very dense flower bed and anytime I need to get in there to trim, I put moth balls in the day before. They smell really bad, but the snakes stay away! Just be sure your animals won't eat them.

Moth balls work but stink. You can also use Seven Dust and make a line around your yard. It works but you have to keep reapplying after rains. They don't like to cross over it. Don't worry so much about them getting bit. My cat & dog have been bit by rattlers and the vet doesn't even give them anti-venom. Cats are the most resilient and dogs second to venom bites. They just need anti-biotics for the bite and pain & swelling meds for the first day.