The first thing you need is two shovels. (You can buy them at Tom Nook's Store) Dig a hole in the ground with one shovel. Then, bury the other shovel in the ground. Now, make sure nobody digs it up for maybe 4 days. After it has been in the ground for 4 days, dig it up again. It will be golden, but how does it effect anything you dig up an bury Well, with the Golden Shovel, you can bury bells and they will grow into trees! Shake the tree and bells (Money Bags) should fall out of it!
(credit goes to cheatcc.com for info)