Should you want to learn how to draw a Mushroom Cloud, just check the steps below.
Draw a mushroom shape. Add on two layered neck. Sketch lines forming its stand. Illustrate the soil where it will stand. Highlight your drawing. Fill out the mushroom shape with the combinations of blue, white and yellow colors. Use black color for the soil. Add blue shadows around your drawing making it appear gloomy. That's how easy it is.