I planted potatoes in my mulch pile. They took off like weeds. I left them alone to do their thing. As the mulch pile broke down, I noticed a potato showing and promptly mounded up more mulch on top of them. I kept my eye on them and mounded the pile up once more. When I dug the potatoes up, the once exposed potato was somewhat green on the topside. The others looked pretty good. After harvesting I left them in the sun in a plastic milk crate on my picnic table for a couple days to let the skin dry a little. When I went to check them, they all turned green. I have never had this happen in the past out of the garden. Is something different, because they were in the mulch pile? Can I eat them? Will they turn brown at all? Do I need to toss them out?
Potatoes turn green when exposed to sunlight. Their sensitivity varies with the variety. The tubers produce the green chlorophyll in preparation for sprouting and growth. Solanine, a glycoalkaloid toxin is also produced. This substance gives the potatoes a bitter flavor and can cause vomiting and diarrhea if enough green potatoes are eaten. The bitter flavor usually prevents people from eating enough to make them sick. You can cut away small areas of green and still have a tasty potato. In the future keep potato tubers covered with soil or mulch while growing in the garden and store them in a cool dark location to avoid the problem.
So if the potatoes were all green I would toss them in the compost and try again next year.