About 5:30 a.m., a large chunk of ice fell through the sky, crashed through her roof and ceiling and shattered into smaller pieces, she said.
"I'm just glad I'm alive, to tell you the truth," Foster said. "I guess it wasn't my time."
One of the smaller pieces of mystery ice struck her on the right side of her forehead, jolting her from her dreams.
"If a bigger piece hit me, I'd probably be in trouble," the 66-year-old grandmother said calmly, sitting in her kitchen on Deerfield Lane in York Township. "It could've been fatal."
When the ice smashed through the roof, "it had a tremendous amount of power to it," she said.
The chunk of ice left Foster with a large bump on her forehead, she said, but after putting some man-made ice on it and lying on her couch for a few hours, the swelling receded. Despite the big bruise on her forehead, Foster said she isn't really suffering.
"I feel good," she said. "I have some stinging ... but I'm feeling pretty normal now."
Her husband, Perry Foster, called York Area Regional Police, she said. After emergency officials arrived she declined an ambulance ride to a local hospital and instead went to her own doctor, she said.
The doctor told her to be careful for the first 24 hours, but that she was probably fine, she said.
Six pounds of ice: Before taking his wife to the doctor's office, Perry Foster, 68, gathered up the largest chunks of ice, put them in plastic bags and put them in his freezer - "right next to the bagels," he said. But first, he weighed them.
"It's six pounds," he said.
The couple obliged a steady stream of reporters in their home by taking out the ice and displaying it on their kitchen counter. It's clear in some areas and whitish in others, and doesn't appear to have debris frozen inside.
"It almost looks like quartz," Mary Ann Foster said. "There is a little fish smell to it, which is weird."
Perry Foster said he was up early Wednesday morning and was downstairs when his wife alerted him to the strange event.
"I was just utterly shocked and surprised," he said.
Home damaged: Perry Foster said the damage to their roof and ceiling is extensive.
"It was a very high-velocity impact," he said.
The ice left a baseball-sized hole in the roof and a bigger hole in their bedroom ceiling, he said.
"It knocked down the ceiling tile and went through the fiberglass insulation, which is hanging down, and there's debris all over the place," Perry Foster said.
By Wednesday afternoon, a work crew had arrived to do a temporary fix until permanent repairs can be made, he said.
York Area Regional Police estimated the hole in the ceiling to be 18 to 24 inches, and said the chunk of ice was probably 18 inches long before it broke up.
What is it? Sgt. Rod Varner said police believe the ice probably fell from an airplane and have notified the Federal Aviation Administration.
"This sort of thing has happened throughout the U.S., so that's what we're assuming it was," he said. "I'm not sure of any other theory the officers are going with right now."
But the Fosters' son-in-law did a bit of Internet research and discovered that scientists "had been predicting there was going to be a meteor shower of ice on Oct. 8 over this region, including Maryland," Perry Foster said. He wondered whether their ice chunk could be connected.
"I'd love to know" where it came from, Mary Ann Foster said.
UCLA professor and meteorite expert John Wasson said he doubts the ice is part of a meteorite shower.
"The fact that it doesn't have any dirt in it is contrary to what you'd expect from a comet," he said. "These things have happened in the past, and inevitably the conclusion has been they have fallen off an airplane."
Study recommended: Still, Wasson said, the ice should be examined to determine its isotropic properties, which should clear up the mystery.
"It's good that they saved the ice," he said.
Wasson said the ice could not have come from the Draconid meteor shower, which is happening now.
"The Draconids have been around for a very long time," he said. "They don't have any ice left. None of the meteors are wet."
Someday, he said, a piece of ice from a comet could hit the earth.
"But all evidence to this point (suggests) it is terrestrial ice that fell off an airplane or rocket."
-- Reach Elizabeth Evans at email@example.com or 505-5429. Staff writer Christina Kauffman contributed to this report.