Unknown Visitor

My mom and I returned to her house after shopping one day to find this photo lying upside down quite neatly on the wooden border of her garden. The back reads "to Elena, my best friend in the whole world Becca '79' ."

My folks have lived in that house since 1983 and raised all three of us girls there, and we have known most of our neighbors. Nevertheless, Mom and I racked our brains for a neighbor that looked anything like this girl or was named Elena or Becca and couldn't come up with ...