The Wishing Well is a feature on Hogwarts Extreme. It can be accessed via the Main Yard. It looks like a small well with a reddish top.
When you access the Wishing Well page, you will be given the opportunity to collect Galleons out of your pocket. Don't worry--they will not be thrown in yet. Click "walk closer". You will now be presented with numerous options, such as "kick it", "sing a song", and "make a wish", among others. If you select "just throw in money" and throw in 5 or more Galleons, you may receive Galleons back. Or not.
It seems to be a much greater amount that is returned than is thrown in. For example, if you throw in 100 galleons, you may recieve over 2000 in return.