Boil eggs for 10-12 minutes, then peel. *See Notes for handy trick.
Cut eggs in half lengthwise, and remove the yolks. Mash yolks with a fork and add mayonnaise, dry mustard, salt, and pepper.
*Optional: Put the yolk mixture into a plastic zip-top bag and snip the end off one corner. Pipe or fill the mixture into the whites.
Cover and chill for at least one hour.