Here is a green lentil (Lens culinaris), although its color is closer to brown. It's a lens shaped legume that is commonly prepared for human consumption by boiling for 10-40 minutes. The earliest evidence of human consumption goes back to 11,000 BC in Greece. Lentils are second only to soy for legumes in their ratio of protein to calorie. The optical device called lens is named after the lentil. This lentil is about 5.6 mm in diameter, and 2.7 mm thick.
Equipment used: Canon EOS Rebel T5i with a standard zoom lens (EF-S 18-55 mm) on a 49 mm long extension tube.