Black on collards and kale
Thank you for contacting Ask an Expert in regards to your kale and collards with black mold. I don’t recommend eating them, particularly since it is in such a great amount. Even if you do wash them and they appear to be clean they are not since mold extends below the surface area.
According to the USDA Food Safety and Inspection Service mold can cause allergic reactions and produce toxic substances called mycotoxins and aflatoxins. Below is an excerpt from their website for handling Firm Fruits and Vegetables (cabbages, bell peppers, carrots, etc.)
[To] Use. Cut off at least 1 inch around and below the mold spot (keep the knife out of the mold itself so it will not cross-contaminate other parts of the produce).
Small mold spots can be cut off FIRM fruits and vegetables with low moisture content. It's difficult for mold to penetrate dense foods.
As for what this infestation is I cannot give you a definitive answer without a physical sample. What I would recommend is for you to take a sample to your local county extension office during their plant clinic hours. The Multnomah County extension office is located at 2701 NW Vaughn St., Suite 450, Portland, OR 97210, (503) 445-4608, Hours: 10am – 2pm weekdays.
If they have a microscope they would be able to see the tiny structures to help narrow down suspects. If they do not have a microscope and you are still curious I know Clackamas County Extension office does, 200 Warner-Milne Rd., Oregon City, OR 97045, (503) 655-8631, Hours: 9AM - 12PM and 1PM - 4PM, weekdays.