I need to know a name of a book but can't remember it?

Question

this girl who's mother had died years ago, now her father's remarried, and she comes across this diary about her mother looking for gold in California, and so she and her step-mother go and try to find what her mother was looking for. It was in this time and the book cover was yellow..

Answer 1

Hope you find the answer. I have starred so I can read it too. Sounds interesting.