Wild roses. They used to be much more abundant when we got more rain during the summer months than we do now, but they still flourish in a few places.
Dogbane, which is poisonous to animals, most especially cattle. It's not really a problem, though, because it tastes so terrible that that the animal usually never eats enough to be harmed. It can cause a rash similar to the one that stinging nettles cause if picked by humans. I keep pulling it up, but it keeps coming back. It grows from two to four feet tall and grows along the edges of the forest and in sunny areas.
Feverfew. I just love this cheerful little plant. So many people up here call it a weed, I suppose because it grows so abundantly in the spring and summer. The flowers are only about the size of a dime, and it usually grows in large clumps along the roadsides and in open clearings in the forest. It gets about two feet tall. It has been used for treating headaches, fever, arthritis and digestive problems, but it can cause nausea, vomiting, pain, contact dermatitis and mouth ulcers if chewed or improperly prepared, so I stick to using the capsules I get from the health food store.