The everlasting egg Egg cartons can bear a number of dates that vary by state and grocery chain, Those that are graded by the U.S. Department of Agriculture must carry a date that indicates the day of the year (001 for January 1 and 365 as December 31) the eggs were packaged. Eggs under the USDA shield may also carry a 'sell-by' date that is no more than 30 days later. Still, eggs can be used for much longer than you might think. You can count on USDA eggs for four to five weeks from the date stamped if the eggs are refrigerated. Absent a stamp, consumers can probably assume an egg will be good for three weeks after they bring it home. After that, the egg white can start to thin out andthe membrane around the yolk can start to weaken. It gets gummy, harder to beat, and finally achieves what Linda Braun of the American Egg Board calls 'perfect dryness': It will literally rattle. If refrigerated, USDA eggs will remain good for ______ weeks from the date stamped.