- Alice Linna Allen Bailey Nightingale, Alonzo Clayton Davis, Arthur William Lindquist, Benjamin Ralph Stauber, Charles Frederick Clark, David Griffiths, Ernest Adna Back, Frank Rabak, Frederick Charles Lincoln, George Arceneaux, Gustaf Adolph Pearson, Harry Lawrence Wilson, Homer Charles McNamara, Hubert Hill Moon, Leon Howard Worthley, Max Raymond Osburn, Olaus Johan Murie, R. Clifford Hall, Roy Magruder, United States. Department of Agriculture, Waldo Lee McAtee, William Doyle Reed, Arthur Clifton McIntyre, Austin Winfield Morrill, Charles W. Culpepper, Frederick James Stevenson, Glen Blaine Ramsey, Houston Vernon Claborn, Joseph William Lipp, Leslie Rushton Hawthorn, Mark Mathew Regan, R. T. Cotton, Robert Theodore Stutts, Walter Van Price, Erskine McFarlane Livingstone, Joseph Stuart Caldwell
· 1935
- Alexander Campbell Martin, Arthur Henry Senner, C. C. Plummer, C. H. Hadley, Chalmers Jackson King, Curtis Paul Clausen, David A. Savage, Ernest Victor Abbott, Frederick Charles Lincoln, Glenn Gardner Hahn, Harold Francis Scholz, Harold Glenn Meginnis, J. Clark Salyer, James Herbert Beattie, Jenkin William Jones, Mayne Reid Coe, Paul William Miller, Ralph P. Hotis, Robert J. Sim, United States. Department of Agriculture, Walter Ernest Fleming, Wilbur Clifford Edmundson, Wilbur Magruder Hurst, Claude Hope, Frederick William Metzger, Ira Myron Hawley, James Robert McCalmont, John Walter Taylor, Victor Rickman Boswell, Walter Raymond Humphries, William Ernest Stone, E. E. Hall, Max Raymond Osburn, Roland McKee
· 1934
- Albert Rudolf Leding, Arnon Lewis Mehring, Arthur T. Sweet, Auton William Skuderna, Benjamin Ralph Stauber, Curtis May, David Griffiths, Floyd Franklin Smith, George Arceneaux, James Fitton Couch, John Morrison Cooper, John Robert Parker, Lewis Alexander Hurst, Orator Fuller Cook, Paul George Russell, Paul Mehl, R. A. Blanchard, R. T. Balch, Robert Max Merrill, Theodore Bergen Manny, United States. Department of Agriculture, Walter Ernest Fleming, Wilfred Wickes Ballard, William Middleton, Asa Young Willis, Avis Jenkin Peterson, Frederick William Metzger, J. I. Lauritzen, John Adam Stoehr, Ralph Brownson Bisland, Wayne Crocker Nason, Max Raymond Osburn
· 1933
- Albert Watts Moore, Carl F. Dunker, Charles D. Converse, Claron Owens Hesse, Elmer Snyder, Everett Eugene Lund, Frank Custer Edminster, Franklin Elmer Allison, Franklin Jacob Crider, George Haymaker Vansell, Guy Weston Bohn, H. O. Hetzer, Harry Edward Goresline, Henry Hamilton Bennett, Herbert Spencer, Jesse Edward Harmond, Leslie Rushton Hawthorn, Myron Sallee Anderson, Oscar Roland Mathews, Ralph William Marquis, United States. Department of Agriculture, Elbert Hann Reid, Forrest G. Bell, Frank Nelson Harmon, Kirby M. Hayes, Leonard M. Klein, Lester Alan Thompson, Max Raymond Osburn, Sidney Fay Blake, Thomas Wallace Whitaker, Alfred W. Otte, Arnon Lewis Mehring, Bert D. Robinson, Paul A. Norman
· 1951