I need your help!!!

So, basicaly, when I was a kid, I had this weird book. It had different puzzels in it, like mental games, and when Du solved the whole book, there would be an exact place were if Du go to and dig a whole, there would be a reward. I'm talking a serius reward like one of those jem figuriens Du see in the windows of diamond stores. I dont know the name of the book, and I was wondering if any of Du knew what it was. I'm pretty sure there isnt a diamond statue somewere underground, I just want the book. Thanks!!!!! :)