Biographies of American Seedsmen and Nurserymen M’Mahon, Bernard–(1775-1816)–Philadelphia, Pennsylvania–M’Mahon came from Ireland in 1796 and began to collect and export seeds of native American plants in 1800.  His catalog of 1804 listed seeds of about 1,000 species.  In 1806, he published his book The American Gardener’s Calendar, that was for 50 years the standard gardening authority in America.  There were eleven editions of his book by the last edition published in 1857.  A general catalog of garden plants was published at the end of the book. He knew Jefferson and his store became the meeting place of botanists and horticulturists.   M’Mahon helped to distribute the seeds collected by the Lewis and Clark Expedition.  M’Mahon died on September 16, 1816.
Sources:  Plants; Woodburn2; Bailey; PHS2; PHS1; CHSJ-Apr. 1966; Leighton1; Leighton2; GT; DAB; Oxford; Hedrick.; Sarudy; Wright