WASHINGTON, May 30 (Reuters) - U.S. Supreme Court Justice Clarence Thomas, who bitterly wrote of affixing a 15-cent price sticker to his 1974 Yale Law School diploma and storing it in the basement, appears to be reconciling with his alma mater.

After spurning overtures by the law school since his 1991 high-court appointment, Thomas has agreed to be the keynote speaker at a Yale Law School alumni dinner at the National Press Club in Washington on June 28. This commitment follows a December appearance at Yale's New Haven, Connecticut campus - which university officials believe marked his first-ever return - when he addressed small groups of students and faculty.

The event, for hundreds of Yale alumni and their guests, will coincide with the scheduled final week of the Supreme Court term and likely just as the court has delivered its ruling on President Barack Obama's healthcare law.

Thomas's bitterness toward the prestigious law school has a complicated history - traceable to the view expressed in his memoir that the degree "meant one thing for white graduates and another for blacks" and exacerbated by the testimony of another Yale graduate, Anita Hill, against his Supreme Court nomination.

Thomas's reconciliation appears to stem from similarly complex factors.

"SOUL-SEARCHING"

"I think this comes out of his own soul-searching," Yale law professor Akhil Amar, who taught a class with Thomas during his December visit, said on Wednesday. "I think ... he wants to feel right with himself. He wants to regain his sense of balance with Yale."

Thomas was traveling and unavailable for comment, said court spokeswoman Kathy Arberg.

Thomas might have revealed some of the regret he felt regarding relations with Yale when he appeared in December, first at the New Haven Legal Assistance Association, where he had worked during law school.

"I have to go over to the law school now," he said, according to an account in the Connecticut Law Tribune. "This is kind of a big deal. I was shamefully bitter towards a school that gave me an opportunity to finish up and do OK. And I've got to go over and do my mea culpas. I was juvenile, and that's the way I feel about it."

In his 2007 memoir, "My Grandfather's Son," Thomas wrote that people at Yale and in the broader legal community suggested he had been admitted at the Ivy League law school because of racial preferences, which were meant to compensate for years of discrimination against African Americans.

"After graduating from Yale, I met a black alumnus of the University of Michigan Law School who told me that he'd made a point of not mentioning his race on his application," Thomas wrote. "I wished with all my heart that I'd done the same. By then I knew I'd made a mistake in going to Yale. I felt as though I'd been tricked, that some of the people who claimed to be helping me were in fact hurting me."

NO TO PAST INVITATIONS

Thomas said he had a hard time finding a job after law school. He eventually landed one with John Danforth, a Yale law graduate who was then Missouri attorney general. Danforth would eventually become a U.S. senator and play a strong role in Thomas's 1991 confirmation.

Through the years, Thomas declined invitations to speak at Yale or to have his portrait painted and hung, as has been the tradition for other law school graduates who have become Supreme Court justices.

During the Senate confirmation hearing in 1991 Hill, who graduated from Yale Law School in 1980, testified that Thomas had sexually harassed her when she worked for him at the U.S. Department of Education and at the U.S. Equal Employment Opportunity Commission. Thomas categorically denied the accusations. The Senate approved him by a vote of 52-48, the closest Supreme Court vote in more than a century.

"Hill-Thomas was civil war at Yale," Amar said. "I think he felt his own institution turned on him."

Amar said several Yale graduates who had become law clerks to Thomas at the high court had been encouraging him to return to the school.

PERSONAL HISTORY

During the session that he shared with the justice in December, Amar said, the focus was on Thomas's personal history and view of the law. Thomas, who will be 64 on June 23, is the most consistently conservative member of the high court. He is also the quietest on the bench. He has not asked a question during oral arguments since February 2006.

In addition to appearing at Amar's class on Federal Jurisdiction, Thomas met with members of the Yale Law School Federalist Society and the Black Law Students Association.

"He was beaming from ear to ear while he was here," said Jan Conroy, director of communications at Yale Law School. "He seemed to have a wonderful time."

Conroy said that the steering committee of the Washington-based alumni group decided to try to invite Thomas to its annual dinner, and Yale Dean Robert Post extended the invitation.

Conroy added, "There is still a standing offer to have his portrait painted."

(Reporting by Joan Biskupic)

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