U.S. officials are urgently seeking an agreement with South Korea that would allow imports of American eggs so farmers can cash in on a shortage caused by the Asian country’s worst-ever outbreak of bird flu. The two sides are negotiating over terms of potential shipments after South Korea lifted a ban on imports of U.S. table eggs that it imposed when the United States grappled with its own bout of bird flu last year, according to the U.S. Department of Agriculture.