- Edgar John Udine, Edmund Lambert, Edward Mackay Chace, Emil George Boerner, F. L. Duley, Franklin Arthur Coffman, George Emil Gaus, Gerard Dikmans, Harold Robert Hochmuth, John Stuart Pinckney, Joseph Benjamin Shepherd, M. A. Yothers, Mark Hughlin Haller, Robert Hale Nelson, Roland McKee, Russell Rutherford Whitten, United States. Department of Agriculture, Victor Leo Stedronsky, W. A. Douglas, W. G. Bradley, William John Reid, William Solomon Porte, Carroll Clayton Cassil, Charles Scott Shaw, Dean Humboldt Rose, Earl Raymond Franklin, Harry August Schoth, Harry Bruce Walker, Latimer Ludwig Kelly, Paul B. Allen, Rhea Emerson Stitt, Thomas Laffin Baggette, Thompson Elwyn Woodward, William Alexander Noel, Arvid John Johnson, Marion Clawson, Paul Lewis Harding, Vinnie Arah Pease, Waldo Harold Kliever
· 1941
- Theodore Peter Dykstra, Alice Louise Robert, Axel Langvad Andersen, Berten Wendell Allred, Charles Wesley Gantt, Clarence Dinsmore Stein, Claude Kedzie Shedd, F. M. Grant, Franklin Thomas Cowan, Fred Charles Simmons, Howard Wilfred Johnson, I. E. Stokes, John Lewis Creech, L. F. Locke, R. W. Leukel, Robert S. Rummell, Ross Calvin Thompson, Thomas Lotti, Tom Dale, Verne Elbert Davison, William John Reid, William Joseph Sando, William Solomon Porte, Rufus F. Dowdle, Claude Carl Wakeland, Clark E. Holscher, Donald William Chamberlain, Floyd Franklin Smith, Frank P. Cuthbert, Grover F. Brown, Otto H. Coleman, Sears Polydore Doolittle, V. F. Tapke, Walton Monroe Nixon, Walter Oliver Hawley, D. J. Caffrey, Jack L. Dean, Samuel George Lehman
· 1955