Plectritis congesta, also known as shortspur seablush, has 1311698 seeds per pound. It is native to western North America from Vancouver Island to southern California, where it is a common plant in coastal forests, seashores, mountain meadows, and other habitat. 
More Info: USDA Plant Guide: https://plants.usda.gov/DocumentLibrary/factsheet/pdf/fs_plco4.pdf