Grinding noise when breaking at speeds of less than 15 mph

I checked my pads and they are fine. What could this be. Its not a load grinding, but it is noticable.
I realy do like this car, but all these problems are starting to piss me off. 3 EGR pipes cracked at 1K miles intervals. Dealer told me they forgot to put a bold on last time, we will see if this fixes it or if I get another egr pipe crack in about 2-3 weeks.

I park on gravel, and after a rain storm enough debris splash onto the disk, drum, and backing plate to cause grinding for the first few brake applications.

I get this, but usually just first thing in the morning. I attribute it to the light rust on the rotors from rain, dew, condensation.