Documents and information from aides to President Carter have been found stored in the files of Ronald Reagan's campaign officials in the archives of the Hoover Institute at Stanford University, Reagan administration sources said yesterday.

They said the material included the missing copy of an Oct. 21, 1980, memo sent by Reagan campaign volunteer Wayne H. Valis to White House chief of staff James A. Baker III. The memo claimed to report details of a "middle-level" Carter staff meeting "from a source intimately connected to a Carter debate staff member."

The sources said the memo copy was found among Baker's papers in a file of exotic campaign proposals labeled "Ed Meese." Edwin Meese III, who was then chief of staff of the Reagan campaign, is now White House counselor.

Baker, Meese, Office of Management and Budget Director David A. Stockman and White House communications director David R. Gergen were interviewed by FBI agents yesterday as part of the Justice Department's investigation into how the Reagan campaign came into possession of Carter White House documents.

Yesterday morning, according to White House spokesman Larry Speakes, President Reagan interrupted a meeting of his senior staff members to tell them, "I want everyone in this room and the White House to continue to cooperate fully with the FBI and to tell everything they know about any of these allegations."

In the afternoon, as Reagan left the White House to spend the weekend at Camp David, he told reporters, "If there is any evidence of wrongdoing, we'll take whatever action should be taken." Asked if that included firing anyone, he said, "Yes."

Asked whether he regretted saying on June 24 that the inquiry was "much ado about nothing," Reagan replied: "No. If, when the investigation is over and the truth is known, it is necessary to correct that statement, I'll correct it."

White House officials said Reagan and some of his aides had become concerned about what one of them called "the leadership perception" of the president in the controversy. As a result, they said, Reagan wanted to reiterate publicly that he was urging full cooperation with the investigation.

The Carter documents found in the files of Reagan campaign officials at the Hoover Institute were described as "innocuous" by administration sources, who said they were found in the files of "more than one" Reagan campaign aide.

Meese said he didn't know whether any of the documents were found in his files. He said some of the campaign files were undifferentiated as to ownership.

"All the materials were packed into boxes and shipped out to Hoover when the campaign was over," Meese said. "The files weren't necessarily segregated as to who had possession of them during the campaign."

The Valis memo found in Baker's files was a copy of one sent to Gergen on Oct. 21, 1980. Baker said in a June 28 memorandum to White House counsel Fred F. Fielding that he had "no specific recollection" of having received the copy, but added, "It is of course possible that one was given to me."

The memo's handwritten cover letter reads: "These notes are based on a Carter debate staff brainstorming session--middle-level types--nothing spectacular, but interesting--from a source intimately connected to a Carter debate staff member. Reliable. I gave a copy to Jim Baker."

The appended, typed notes, headed "Proposed Carter tactics for debate and campaign advertising," contain a number of basic Carter strategy proposals, such as exposing Reagan "flip-flops" and calling him a "warmonger." They also contain proposals the Carter campaign never used, such as political ads featuring interviews with Reagan's classmates to show how old they were.

Baker had been campaign manager for George Bush when he was Reagan's chief rival for the 1980 Republican presidential nomination. Baker's primary role in the Reagan campaign was negotiating the debates with Carter and independent candidate John B. Anderson.

Gergen was in charge of debate preparation, and Stockman served as the stand-in for Anderson and Carter in debate rehearsals. Stockman has said he was helped in his role by "pilfered" Carter White House debate briefing papers.

Baker has said that he was given the Carter briefing papers by Reagan campaign manager William J. Casey, now CIA director, and that he passed them on to Gergen. Casey has disputed this and has said Baker was "remiss" in not calling attention to the papers within the Reagan camp.

The finding of more Carter documents in the Hoover Institute archives demonstrated one of the difficulties in the Justice Department's investigation, the widespread dispersion of campaign materials. The probe, one administration official said this week, is likely to take all summer. The search at Hoover, being conducted by two archivists, is expected to take two more weeks to complete.

Pertinent material will be shipped directly to the Justice Department, White House officials said. One official said the White House will tell Rep. Donald J. Albosta (D-Mich.), chairman of a House subcommittee conducting its own investigation, that it will be impossible to comply with his request for documents found at Hoover.

"We'll tell him what we know, but it will be up to Justice to tell us," one official said. "We're not going to see the files that are at Hoover."

In the latest response by a Reagan administration official to inquiries from Albosta, U.N. Ambassador Jeane J. Kirkpatrick said she knew nothing of Carter White House debate briefing papers when she also helped prepare Reagan for his Oct. 28, 1980, debate with Carter.

"At no time . . . did I notice any activity which might have even remotely suggested use of Carter campaign materials," Kirkpatrick wrote to Albosta.

Questioned Thursday by investigators for Albosta's subcommittee, former Reagan campaign adviser Richard V. Allen said he was told by someone he could not recall that a Carter National Security Council aide, Jerry D. Jennings, was the source of Carter NSC staff memos that Allen said he received during the 1980 campaign, according to informed sources.

Jennings, now executive director of science and technology policy in the Reagan White House, has denied this.

"Any such suggestion is untrue and absolutely ludicrous," Jennings said when first asked about it by The Washington Post a week ago. After consulting with aides to Gergen and Fielding, Jennings added, "You would be in error in publishing something that is clearly libelous."

In 1981, when Allen was Reagan's national security affairs adviser, Jennings reported the discovery in Allen's office safe of $1,000 in cash from Japanese journalists who had interviewed Nancy Reagan. This was among events that led to Allen's resignation.

On Thursday, Allen told Albosta subcommittee investigators that he was given Jennings' name by someone who handed him the envelope containing the Carter NSC staff memos during the 1980 campaign, according to informed sources. But they said he added that he could not remember the name of that person, nor has he been able to locate copies of the memos he received.

Allen has emphasized that the materials he received were "innocuous" and dealt only with "atmospherics," such as the morale of the Carter National Security Council staff. Carter national security affairs adviser Zbigniew Brzezinski has said the daily reports prepared for him by each of his 30 staff members included classified material.

Until Reagan's appearance at yesterday's meeting of his senior aides at the White House, his advisers had said he should avoid calling in his staff and conducting his own inquiry because he might be accused of covering up information.

But they became concerned in recent days, according to officials, about the public perception of Reagan as being reluctant to deal with the situation and not controlling his staff.

"He doesn't need to call everyone into his office and start an investigation," one Reagan adviser said. "He does need to say again and again that he wants this case out in the open for all to see and with all of his staff available for any questions. He's been saying that, but it hasn't come through as loudly as we would like to."

Apparently acting on that advice after his early morning meeting yesterday with Baker, Meese and deputy chief of staff Michael K. Deaver, Reagan went to the 8:15 a.m. staff meeting in the Roosevelt Room across the hall from the Oval Office and told aides to cooperate with the FBI, Speakes said. He quoted Reagan as saying, "We want to get to the bottom of this and we want it out in the open."

Turning to Meese, Reagan said, according to Speakes, "Ed Meese, see to it that the Cabinet and everyone else in the administration are instructed likewise."

Looking at Fielding, the president reportedly said, "Fred, tell the FBI that everybody is cooperating fully and will be available for questioning, including me. We want the truth."

Reagan then got up and walked out, without any conversation with his staff, according to Speakes. He said Cabinet secretary Craig L. Fuller, who had been giving a staff report when Reagan walked in, picked up where he had left off without making any comment.

"It was an eye-to-eye session with his senior staff," Speakes said.

Later in the day, as Reagan was leaving for Camp David with his wife, he explained why he had taken the action and allowed his aides to publicize it: "In view of all that's been going on I thought they should hear it directly from me."