Question: Edgar Rickard was a confidant of which 31st President of the United States?

full_context: Document 1: Consolidated Zinc: Consolidated Zinc was an Australian mining company from 1905 to 1962. The company's initial operations focused on extracting zinc from mine tailings of the Broken Hill Ore Deposit at Broken Hill, New South Wales, Australia. The company was founded in Melbourne on 9 September 1905 as the Zinc Corporation Limited, to exploit residual zinc concentrations with an estimated value of $12 million in the 6 million tons of mine tailings deposited from mining activities over the previous 20 years. Key figures involved in the effort included William Baillieu and William Sydney Robinson. Also involved was future U.S. president Herbert Hoover, who inspected the tailing dumps as a mining engineer in the group's investigations prior to formation of the company.
Document 2: Eddie Rickenbacker: Edward Vernon Rickenbacker (October 8, 1890 – July 23, 1973) was an American fighter ace in World War I and Medal of Honor recipient. With 26 aerial victories, he was America's most successful fighter ace in the war. He was also considered to have won the most awards for valor by an American during the war according to the April 2017 VFW magazine in their special World War I edition.
Document 3: Herbert Hoover National Historic Site: The Herbert Hoover National Historic Site is a unit of the National Park System in West Branch, Iowa, United States. The buildings and grounds are managed by the National Park Service to commemorate the life of Herbert Hoover, the 31st President of the United States. The park was established in 1965, shortly after it was named a National Historic Landmark. It now encompasses 186.8 acre .
Document 4: Calvin Coolidge: John Calvin Coolidge Jr. ( ; July 4, 1872 – January 5, 1933) was the 30th President of the United States (1923–29). A Republican lawyer from Vermont, Coolidge worked his way up the ladder of Massachusetts state politics, eventually becoming governor of that state. His response to the Boston Police Strike of 1919 thrust him into the national spotlight and gave him a reputation as a man of decisive action. Soon after, he was elected as the 29th vice president in 1920 and succeeded to the presidency upon the sudden death of Warren G. Harding in 1923. Elected in his own right in 1924, he gained a reputation as a small-government conservative, and also as a man who said very little, although having a rather dry sense of humor.
Document 5: Bob Rickard: Robert "Bob" J M Rickard is the founder and editor of the UK magazine "Fortean Times: The Journal of Strange Phenomena", which debuted in 1973 under its original title "The News". The magazine's express purpose is to continue the documentary work of Charles Fort on the strange, anomalous and unexplained. In addition to his editorial role, Rickard has written several books and hundreds of articles on a wide range of Fortean topics. In 1981, he was a founding member of ASSAP and is also the founder of the Charles Fort Institute.
Document 6: Minthorn Hall: Minthorn Hall is an academic building on the campus of George Fox University in Newberg, Oregon, United States. Built in 1887, the hall was moved ten blocks to its current location in 1892. The three-story frame building is the oldest building on the campus of the school, and was the first building of the Quaker school. Future President Herbert Hoover may have briefly lived in the structure prior to its conversion to a school building. The hall was added to the National Register of Historic Places on June 13, 1997.
Document 7: Electoral history of Herbert Hoover: Electoral history of Herbert Hoover, 31st President of the United States (1929–1933) and 3rd United States Secretary of Commerce (1921–1928).
Document 8: Great Depression: The Great Depression was a severe worldwide economic depression that took place mostly during the 1930s, originating in the United States. The timing of the Great Depression varied across nations; in most countries it started in 1929 and lasted until 1941. It was the longest, deepest, and most widespread depression of the 20th century. In the 21st century, the Great Depression is commonly used as an example of how far the world's economy can decline.
Document 9: Inauguration of Herbert Hoover: The inauguration of Herbert Hoover as the 31st President of the United States was held on Monday, March 4, 1929, at the east portico of the United States Capitol in Washington, D.C.. The inauguration marked the commencement of the only four-year term of Herbert Hoover as President and of Charles Curtis as Vice President. Chief Justice and former President William H. Taft administered the presidential oath of office to Hoover. This was the first time a Presidential inauguration to be recorded by sound newsreels. It was also the second (and most recent) time that a former president administered the oath of office to a new President.
Document 10: Franklin D. Roosevelt: Franklin Delano Roosevelt ( , his own pronunciation, or ; January 30, 1882 – April 12, 1945), commonly known as FDR, was an American statesman and political leader who served as the 32nd President of the United States from 1933 until his death in 1945. A Democrat, he won a record four presidential elections and emerged as a central figure in world events during the mid-20th century. He directed the United States government during most of the Great Depression and World War II. As a dominant leader of his party, he built the New Deal Coalition, realigning American politics into the Fifth Party System and defining American liberalism throughout the middle third of the 20th century. He is often rated by scholars as one of the three greatest U.S. Presidents, along with George Washington and Abraham Lincoln.
Document 11: Edgar Rickard: Edgar Rickard (January 17, 1874 – January 21, 1951) was a mining engineer and lifelong confidant of U.S. President Herbert Hoover. He was the son of mining engineer Reuben Rickard, and the brother of Thomas Rickard, a mining engineer and one-time mayor of Berkeley, California. He was born on January 17, 1874 in Pontgibaud, France. For many years around the turn of the century, he was the editor of a mining journal in London.
Document 12: Hoover Moratorium: The Hoover Moratorium was a public statement issued by U.S. President Herbert Hoover on June 20, 1931, which he hoped would ease the coming international economic crisis, as well as provide time for recovery. Hoover's proposition was to put a one-year moratorium on payments of World War I and other war debt, postponing the initial payments, as well as interest. Many were outraged by this idea. This statement was met with disapproval from France, as well as many US citizens. Despite this negative reaction, it went on to gain support from fifteen nations by July 6. The moratorium was approved by Congress in December.
Document 13: Herbert Hoover: Herbert Clark Hoover (August 10, 1874October 20, 1964) was an American engineer, businessman, and politician who served as the 31st President of the United States from 1929 to 1933 during the Great Depression. A Republican, as Secretary of Commerce in the 1920s he introduced Progressive Era themes of efficiency in the business community and provided government support for standardization, efficiency and international trade. As president from 1929 to 1933, his ambitious programs were overwhelmed by the Great Depression, which seemed to get worse every year despite the increasingly large-scale interventions he made in the economy. He was defeated in a landslide in 1932 by Democrat Franklin D. Roosevelt, and spent the rest of his life as a conservative denouncing big government, liberalism and federal intervention in economic affairs, as Democrats repeatedly used his Depression record to attack conservatism and justify more regulation of the economy.
Document 14: Andrew Mellon: Andrew William Mellon ( ; March 24, 1855 – August 26, 1937) was an American banker, businessman, industrialist, philanthropist, art collector, and politician. From the wealthy Mellon family of Pennsylvania, he established a vast business empire before transitioning into politics. He served as United States Secretary of the Treasury from March 9, 1921 to February 12, 1932, presiding over the boom years of the 1920s and the Wall Street crash of 1929. A conservative Republican, Mellon lowered taxes and government spending in the aftermath of World War I.
Document 15: Lou Henry Hoover House: The Lou Henry Hoover House or, very rarely, Lou Henry and Herbert Hoover House, located on the campus of Stanford University in Stanford, California, United States, is the former house of Herbert Hoover, 31st President of the United States, and his wife Lou Henry Hoover, who designed it. It is now the official home of the president of Stanford.
ground_truth: Herbert Clark Hoover