I'm hoping that this will ring a bell with someone. A fellow baby
boomer and I both read a "young adults" book while pre-teens. It
begins with a young girl, depressed at the end of her family's summer
vacation at a lake, picking up a moon-shaped stone. We don't remember
much else, but there is the heroine's triumph at a high school dance
(i think she has just become a freshman). Also, we both recall that
she has a cousin who sews dresses with things like hot dog appliques
on them. (I suppose this was supposed to reflect 1960s fashion.)
Lastly, I remember that the heroine's boyfriend makes a bracelet for
her out of wire. We believe that the author's first name was Barbara,
and that the surname began with an "S", but we cannot be sure. Thought
we should give Google Answers a try.

Hi, you might want to try asking this question on the "stump the
bookseller" site at http://www.logan.com/loganberry/stump.html