Robert's a stinker

This pretty little flower is common in woods and gardens, where it seeds very easily.  It's a geranium, Geranium robertianum, but why it's called Herb Robert is a mystery. 

 In some districts it is known as Stinking Bob, because the leaves, which turn red in autumn or in dry conditions, have a very strong smell.  Most people find it disagreeable, but I rather like it.  You sometimes smell it before you see it.