Summary[edit] Description: Seeds of the American Pennyroyal (Hedeoma pulegioides). Date: 17 February 2008. Source: USDA [1]. Author: Jose Hernandez @ USDA-NRCS PLANTS Database. Permission (Reusing this file): This image is not copyrighted and may be freely used for any purpose. Please credit the artist, original publication if applicable, and the USDA-NRCS PLANTS Database. The following format is suggested and will be appreciated.