One day, back in the mid 1960s, a young mother named Elaine Lobl Konigsburg was strolling through the Metropolitan Museum of Art when she noticed something strange: a piece of popcorn sitting on a blue satin chair in one of the 18th-century rooms.
“No one could have gotten past the velvet rope to where that popcorn was,” the author’s son Paul told The Post. “My mom and sister wondered whether it was a guard that left it — or if someone was sleeping there.”
That kernel would inspire Konigsburg’s classic children’s book “From the Mixed-Up Files of Mrs. Basil E. Frankweiler,” about two young siblings who run away from home and camp out at the Met. “Files” turns 50 this year, and while Konigsburg passed away in 2013, her children remember the creation of the book as if it were yesterday.
When their mom — who wrote as E. L. Konigsburg — was working on the book, “We would come home from school for lunch and she would read us a chapter or two,” said middle child Laurie, now 60. “She wanted to see if we laughed.”
The Konigsburgs lived in Port Chester, just north of the city. Every Saturday, Elaine — an ex-chemist and art enthusiast — would take the train into Manhattan, dropping her kids off at the Met before going to a drawing class and later joining them.
Konigsburg knew exactly the type who would try sneaking into the Met and leave a piece of popcorn lying around: her urbane kids, who had complained about the crawling ants and melting food during a picnic at Wyoming’s Yellowstone National Park.
“If any of us decided to run away from home, it would be to some place nicer,” said Paul.
Konigsburg illustrated “Files,” too, and used Laurie and youngest son Ross as visual inspiration for the runaways Claudia and Jamie.
“She would tell us where to stand and what our expression should be and then take Polaroid pictures and draw from them,” said Laurie.
“Files” was one of two manuscripts Konigsburg, a brand-new author, submitted to publishers. Amazingly, both were picked up by Atheneum Books and released in 1967. “Files” ended up winning the 1968 Newbery Medal, the country’s highest honor in children’s literature, while the second book, “Jennifer, Hecate, Macbeth, William McKinley, and Me, Elizabeth,” was a runner-up. No one else has accomplished that double honor to this day.
Konigsburg went on to write 20 kids’…