Bittersweet Nightshade
This perennial plant isn’t as toxic as some of the others on this list, but it’s still poisonous to humans and pets who accidentally ingest their red berries. The clusters of purple flowers are beautiful to look at but don’t be fooled by their beauty. A beast is lurking beneath those flowers. You’ll get headaches, a rash, hallucinations, convulsions, and possibly even death if you ingest the berries, and children are especially susceptible (King County).