I don't think I'd harvest this "mushroom" for a sir-fry (-holding my hand over my mouth). I was thinking it looks like a nodular melanoma- they're mushroom shaped & according to Banner Health (& to be clear, they weren't discussing frogs): "Nodular melanoma is the second most common type of melanoma. It's fast-spreading and grows down into the skin. It's a raised growth, shaped like a mushroom, usually black, red, pink or skin colored."
Yes, they really needed to verify this "find".