There is one spot in my garage no where near any water pipes that has water leaking through the foundation. Although we had a ton of rain over the summer, we havn't had rain for a while. My pipes are in the attic, so you can see why this confuses me, and the three plumbers I've called...suggestions?

Is the leak appearing along the wall or somehere in the middle?
If its along the edge of the wall. Is the floor of the garage below the grading on the outside of the house? That could be one cause. Many builders do not do exterior water proofing in areas that are not considered living space such as a garage. You may have to install a exterior water proofing system where the water is coming in. Another cause could be an outside faucet leak. Or a leak that is traveling along the interior framed wall and coming out at that location.
Need more information about the layout of the garage really to answer this question.