Witch Weed — Phyllis Reynolds Naylor

"""One of the most feared of a witch''s powers is that of the evil eye...""
After throwing Mrs. Tuggle''s evil glass eye into the creek, Lynn and her best friend, Mouse, anticipate a soothing summer. But when Lynn notices some strange-looking purple plants growing down by the creek, she begins to worry. Is she imagining it, or are the plants sprouting right near where she threw the eye?
What''s worse is that some girls from school may be starting their own coven of witches -- and Mouse might be getting sucked in!
Does Mrs. Tuggle have unfinished business with them? And if so, can Lynn fight her evil again?"