From 1915 to 1923, Carver concentrated on researching and experimenting with new uses for peanuts, sweet potatoes, soybeans, pecans, and other crops, as well as having his assistants research and compile existing uses. This work, and especially his speaking to a national conference of the Peanut Growers Association in 1920 and in testimony before Congress in 1921 to support passage of a tariff on imported peanuts, brought him wide publicity and increasing renown. In these years, he became one of the most well-known African Americans of his time.