Do you have a Stop & Shop nearby? If so you'll want to go here to register your card, or apply for a new card. When you register your Stop & Shop card, you will get FREE eggs and milk loaded to your card.
According to the site, no coupon is necessary and when you scan your card the items' (1 dozen brown or white stop&shop eggs and 1 pound of stop&shop butter) prices will automatically be deducted from your order. Can't beat free eggs and butter!