Heat oven to 350 degrees. In a bowl combine the flour, baking soda and salt, mix well and set aside.
With a hand mixture, beat butter and both sugars until creamy. Add eggs and vanilla and mix well. Add the flour mixture in batches until thoroughly combined. Add the oats and mix. Add the M&Ms and combine. I had to take a spoon to mix in the M&Ms at the end because the mix is very thick.
With a tablespoon scoop out the dough and drop rounded tablespoonfuls on ungreased cookie sheets. Make sure the cookies are about an inch and a half apart.
Bake for 10-12 minutes or until lightly golden brown. Take out of oven and let cool on cookie sheet for a minute. Using a spatula take cookies off the cookie sheet and let cool completely on a wire rack.