I got this craft from one of my favorite blogs - No Time For Flash Cards. It's really simple.
Get a piece of blue construction paper for the background. Get a green piece of construction paper and let your child scribble all over it. Cut out the letter "M" shape and glue it onto the blue piece of paper. Cut out two white clouds and two white snow caps and glue them on in the appropriate places. Voila!
M is for Mountain!