Note: This page is in desperate need of updating, with pictures and statistics. For now, this person’s tweet will have to do.
Some days, a glowing spot will appear somewhere on your island. When this spot is dug up, you receive 1,000 Bells. That’s a pretty sweet bonus, but it’s not the end of the story.
After digging up your Bells, the hole will continue to glow. Should you bury Bells in this hole, a money tree will grow. Once fully grown, it will yield triple what you buried, up to a maximum of 30,000 Bells.
So, for maximum rewards, don’t just dig up your glowing spots and run off when you see them. Instead, dig them up and then plant 10,000 Bells.