Catnip! Nepeta cataria -- makes cats go crazy, very easy to grow, and obviously fragrant. It is also a great flower to grow to attract butterflies as it produces many many small purple flowers. Generally reseeds itself, and can come back year after year.
Poison Hemlock seeds! Eat it, you die - it is pretty toxic, but for how common it is , it is obviously not a hazard. A lot of bee keepers grow this near their bee housing(?) to help increase honey production as it is a plant that produces lots of nectar for bees and other insects such as butterflies. Likes to grow near water.
Tobacco Plant This plant comes from the same family as the Nightshades and this genus also contains the plants commercially grown to produce tobacco. It contains piperidine alkaloids which are found in poison hemlock, and the pyridine alkaloid Nicotine which has insecticidal properties . Could cause fetal abnormalities in livestock and mso best avoided in tortoises.
Oh is that Marijuana? No - but it is a plant that is often sold to look like Marijuana! It is Hibiscus cannabinus - also known as Kenaf. 100 seeds for $3.50, free shipping. This, much like hemp, is notorious for the strong fibers it offers. It grows very very tall.
nicotiana tabacum, the tobacco plant, nicotine comes from the dried leaves of the plant and is HIGHLY toxic. causing excitement and eventual depression of the central nervous system, causes respiratory failure, and birth defects