Cream Butter in a bowl.Add white sugar and brown sugar to butter and mix well.
Add the eggs one at a time, mix well.
Mix the flour with the baking soda and salt, add to the egg and butter mixture.
Add the peanut butter and vanilla.
Roll into a ball a little larger than a marble.
Place on an ungreased baking sheet.
Dip a fork into flour and make crisscross design on cookies, pressing out flat.
Bake at 350° for 8-10 minutes.