Rookie Questions About Brake Squeal

About a year ago, I desperately needed four new tires on my 2006 Tacoma. I found a special at Firestone and got them changed there. I also needed my front brakes done, so they cut the rotors and changed the pads for me at the same time. Ever since then, I noticed that my brakes would squeal when backing up (mostly first thing in the morning). I initially (and naively) thought that the squeal would go away after the brakes "wore in", but that's obviously not the case. Firestone wouldn't warranty the brake change and fix the squeal, so I'm on my own. Anyhow, I finally have some time now to do something about it and think that putting OEM Toyota brake pads on may solve this is. They used Wagner Thermoquiet pads or something like that. Does anyone have any suggestions for fixing the brake squeal? Where can I get OEM Toyota brake pads?