Some plantings are for the birds! This entire bed was planted by wind and birds. All I did this summer was weed out everything that wasn't Perilla, Flowering Tobacco and Petunias. BHG.com has the scoop on Nicotiana at http://www.bhg.com/gardening/plant-dictionary/annual/flowering-tobacco/
The bed is under a dead black walnut tree and the entire area was covered with newsprint and a few inches of hardwood mulch. Last spring when it became obvious that the tree had died, we moved all the hardwood mulch to the perennial bed behind. The newsprint had all been eaten by earthworms of course. That's what they do so well.
Perilla is known for generously re-seeding itself. The original seeds were sent to me 5 years ago by my cousin in Germany where they are called Rotes Basilikum (red basil). Since then, they have returned each year but only a few plants.
Did you know that before Coleus became so popular, Perilla was the red/purple foliage plant of choice.
Hort.Purdue.edu explains it's culinary uses, "Perilla foliage "kkaennip namul" and seed oil are used in Korean cooking. Korean markets in the United States sometimes sell perilla. An Oriental grocery in Ames, Iowa, sold bundles of fresh leaves for $6.53/kg in August, 1991. Perilla was an important vegetable in ancient China, but use in modern times has declined there. In Japan, the foliage of "shiso" serves as a garnish. The foliage also provides a red (anthocyanin) food coloring; specialized red-leaved perilla varieties are used in the preparation of pickled plums. In addition to food coloring, perilla adds an antimicrobial substance to pickled foods. Perilla seeds are eaten in Japan and in parts of India. More at http://www.hort.purdue.edu/newcrop/proceedings1993/V2-322.html.