Combine flour, baking soda, salt and sugar in a bowl. Place the mixture in a 1 quart jar.
Next, layer brown sugar, oats, chopped pecans, chips and Reese's Pieces.
Leave a note with the following instructions: Preheat oven to 375° F. Beat 1/2 cup softened butter or margarine, 1 large egg and 1/2 teaspoon vanilla extract in large mixer bowl until blended. Add cookie mix and mix well. Drop by rounded tablespoon onto ungreased baking sheets. Bake for 8 to 10 minutes. Cool on baking sheets for 2 minutes; remove to wire racks. Makes about 2 dozen cookies.