Phyllis Klingebiel has spent her life quietly giving to others.

She and her husband, Herbert, have opened their Rahway home to 67 foster kids over the past 30 years.

This week, one of those children returned to give something back to his foster mother. A kidney.

Mark Greshan came to the Klingebiel household as a skinny 7-year-old and became a headstrong teenager who stayed out late with his friends and gave the Klingebiels more than a few sleepless nights. But he is now in the Navy, and his picture hangs on the living room wall of the Klingebiel home.

On Tuesday morning, the young man do nated his left kidney to the ailing Klingebiel, the only woman he calls "mom."

"I couldn't picture me without my mother," he said.

By Wednesday, Phyllis Klingebiel, 68, was well enough to dictate a grocery list to her husband from her hospital bed, and Mark Greshan was awake and watching ESPN SportsCenter from his bed two floors up. Phyllis Klingebiel has suffered for 20 years with nephritis, a genetic kidney condition. It worsened dramatically in the last year and doctors told her she needed a new kidney.

The wait for a transplant could be up to seven years, Shamkant Mulgaonkar, chief of the transplant division at Saint Barnabas Health Care System, told her.

When Greshan learned his mom would face years of regular dialysis while waiting for a new kidney, he didn't hesitate to offer his.

Greshan, 23, who enlisted in the Navy after graduating from Rahway High School, has spent the last nine months traveling between his Navy base in Florida and Saint Barnabas Medical Center in Livingston for a battery of tests that determine compatibility. The Monday before Thanksgiving, Greshan finally got the go-ahead from St. Barnabas doctors.

The next call he made was to his mom.

"He called me up and said, 'I have a Christmas gift for you,'" Phyllis Klingebiel said. "'The bad news is that it's going to be early. The good news is that you're going to get my kidney.'"

The transplant will dramatically extend Klingebiel's life, Mulgaonkar said. "If you're going to live 10 years on dialysis, you'll live 20 years with a transplant," he said.

Though the number of organs transplanted from nonrelated living donors has grown in recent years, living donors must go through tests to ensure the do nated organ isn't rejected.

Usually family-related donors work best, but not in Klingebiel's case. Herbert Klingebiel has health problems of his own and the Klingebiel's biological daughter, Lisa Jaco, 34, was the wrong blood type.

Her other biological child, son Michael, 46, didn't make any overtures. The two were involved in a bitter dispute in 1997 over a $2 million Pick-6 lottery jackpot.

Phyllis claimed they had an oral agreement to split any lot tery winnings and she went pub lic with her case. The case was settled out of court when Michael Klingebiel agreed to pay his mother a $24,525 annuity for 19 years. Michael Klingebiel has had no contact with his parents or sister since the suit, Herbert Klingebiel said.

"It's like the Bible and the prodigal son,"' Herbert Klingebiel explained. "If he came into the house, I'd say 'that's my son.' But it's on him."

But for the son who did offer his kidney, Phyllis Klingebiel is deeply grateful.

"I'm forever indebted to this young man for this gift," Klingebiel said of her foster son. "He's a walking angel on this Earth."

Greshan stayed with the Klingebiels for about 11 years, longer than most of their other foster children, and felt a genuine sense of belonging.

"After six months, I knew this was my home," he said Monday at the family home, his solid, 6-foot frame taking up a bit more than half of a two-seat sofa. "It wasn't 'foster child,' it was 'son.'" Only two photographs hang in the Klingebiel living room: Phyllis and Herbert's wedding picture and the portrait of Greshan in his Navy uniform.

"I'm doing it for the family, for everyone from the grandchildren on up," Greshan said of his kid ney donation. The Klingebiels have four grandchildren and are raising two teenagers they adopted.

The Navy, who Greshan calls his "second family," has given him leave for the surgery and recovery time. After less than a month of rest, he'll be back at work, albeit on light duty. The loss of the kidney should have no negative impact on Greshan's life. In fact, the remaining kidney normally grows larger and stronger to compensate for the loss.

Josh Rasmussen, who works alongside Greshan on the USS Underwood, said he's proud of his shipmate.

"He's a great guy, he's a good guy to be around," Rasmussen said by phone from the frigate's quarter-deck. Rasmussen will be one of several shipmates working extra duty to make up for Greshan's absence.

Greshan returned home on Thursday; Phyllis Klingebiel is slated to return home tonight, but she'll already have her Christmas present from one of her sons.

"There's nothing I can give him," she said. "I'm just his mom, that's it."

Her husband sees Greshan's generosity as a reward for his wife's years of kindness to children. "God gives everybody a gift, and I guess her gift is helping children," Herbert Klingebiel said. "I guess this just came around and God gave it back hundredfold, back to my wife."