I would throw out the moldy FQs. My vinegar suggestion (on page 1- one cup white vinegar, to one gallon HOT water) was for the fabric stored in plastic bags, which may have mold/mildew spores in it.

I would think that any mold spores would be killed in the dryer as long as you dried the fabric thoroughly. I would toss the moldy ones and the ones that don't show mold, use one of the methods mentioned previously and then dry them well in a hot dryer and you should be good.

No way would I throw it out without first trying to save it!!! You may have a quilter's goldmine there - wash it all in the hottest water possible using Odo-Ban or Oxi-Clean. Then I'd dry and iron it - see what it looks like after! It is so against my grain to toss fabric without first trying everything possible to bring it back to life.

I would cut off the areas that cannot be saved and I would do this outside. I would then hang the fabric or leave the fabric outside exposed to the sun because sunlight kills mold spores. The brighter the sunlight and the longer outside the better. I would then sort the fabric putting like colors together and start washing load by load with bleach for whites, colorfast bleach for colors or you can use vinegar in the washes in place of bleach. Instead of drying in my dryer I would hang outside again to expose to more sunlight. If that doesn't work then I would have no recourse other than to toss it. But like I said I would do the beginning part outside. I would not want the mold spores in the house. Good Luck.

Three weeks is kind of a long time to wait to start doing anything with the fabrics -

The pieces with visible mildew, I would chunk, the rest I would try washing with one or more of the products the other posters are suggesting.

Personally, I'd throw it ALL away, along with the bin. Here's why.

Mold spores cannot all be seen so you really can't judge what LOOKS mold free to actually BE mold free.
There is no way to know how long it's been sitting in that condition or whether the bagged fabrics were bagged up only for the yard sale because they looked cleaner than the others.
It clearly came from a source that had very low standards of care.
There is a risk of spreading spores to other areas of your stash, house, etc.
Someone who is extremely mold sensitive may wind up with a quilt made from these fabrics.

The risk, work, and worry are not worth it to me. I'm just not that desperate for fabric.

I would serger all the end and then wash it all (FQ and all) but that's me.

Thank you all for your input. I decided that I would not take any chances with the fabric and I threw everything, including the plastic tote, in the trash.

I hated to see so much fabric thrown away, but I would always wonder if there was mold in the fabric.

Thank you all.

A very wise decision. I'm sure you won't regret it. :)