All the coins tossed into the wishing well (as well as any Disney fountain anywhere in their parks, resorts or hotels) are collected and the proceeds donated to local children's charities.
Originally, it was put into a trust established between Disneyland and the Variety Clubs International, to go to such places as orphanages, schools, and children's homes.
The trust was terminated in 1972 when federal regulations restricted contributions to foreign charities, and so now it goes to domestic children's charities.
So not only will your wish come true, but your coins will help make the wishes of children come true too.
So go ahead, close your eyes, make a wish and part with a sheckle or two.
And don't be surprised, if you listen closely, to hear a voice from the well telling you that "Wishes are wonderful... Wishes are so much fun!"