Virginia Tobacco Plant (Nicotiana tabacum)
The seeds of Nicotiana tabacum are really tiny, the weight of 1000 is 0.1 gr. This and its high germination rate make planting seedlings difficult as too many seedlings complicate separation for replanting. A trick is to mix the seeds with the triple the amount of fine sand.
It is legal in Spain, Germany and many other countries to grow tobacco for personal use.