Thank you all for so much great advice!!!
The fabric had been sitting in a plastic tote for 3 weeks at my sister's home.
When we met last weekend, the fat quarters were still damp. When I started to look through the tote, I could see many black spots. I knew that there were around 20 fat quarters that were very moldy.
It took me 3 days to decide to throw it all out. I had such a hard time to decide whether to try to salvage some of the fabric or to just not take any chances with the mold and mold spores.
I would feel just awful if I decided to use the fabric for a gift and then the recipient would have health issues from undetected mold spores.
I believe I made the right decision.