Here are seeds of motherwort (Leonurus cardiaca), a perennial plant in the mint family. Thought to be native to southeastern Europe and central Asia, it's now found around the world because of its role in herbal medicine, where it's used to reduce anxiety and blood pressure. The seed size is about 0.7 by 1.8 mm.
Equipment used: Canon EOS Rebel T5i with 49 mm long extension tube.