Follow the steps in order for the best result.
Begin by melting the butter in a saucepan over medium heat. Ensure the pan is large enough to accommodate all ingredients.
Add the sliced mushrooms to the melted butter. Cook, uncovered, over medium heat, stirring occasionally. Continue cooking until the mushrooms have softened and are tender, approximately 5 to 7 minutes.
Incorporate the thawed and drained corn, chopped green onions, salt, and pepper into the saucepan with the mushrooms. Stir gently to combine all ingredients evenly.
Continue to cook, stirring occasionally, until the corn is heated through and the green onions have softened, about 5 to 7 minutes. Adjust seasoning to taste.