Finding Free Baby Yarn for Charity Project?

I have begun a group of women who knit/crochet baby hats, booties, sweaters, and blankets for the Pediatric Interum Care Center in Kent, Washington. This is the only nursery in the state of Washington that deals with babies born into drugs. These little ones have nothing. Most, after having the drugs taken out of their system, go into homes that will care for them in their next phase.

These little ones need a new lease on life and a second chance, we are trying to provide this in a small way. We do need pastel baby yarn to assist in making these things. I provide the yarn free to all who would like to help with this project. Do you know where I could get some free or minimal cost yarn? We can only use pastel baby yarns. These
little ones cannot handle other colors during and shortly after these drugs are through their bodies.

Thank you.