There are a couple of stories. The most common is that an evil inn keeper stuffed a couple of boys in a pickle barrel. Santa found them and freed them with his magical staff. To celebrate the boys being saved, families hang a glass pickle on the tree. The pickle, being the same color as the tree is hard to find. The first child to find the pickle gets an extra gift from Santa.
In my family it was a Christmas Pig made of marzipan (ground almonds). aka a "Jul gris".
Norway
Yes, but often, it is not a real pickle. It is usually a Christmas ornament that looks like a pickle. They are usually made of blown glass.
some people say they hide a pickle ornament in a Christmas tree and if a child finds it they get an extra gift from St.Nick but nobody in Germany had even heard of this tradition.
The pickle tradition is that the parents hide the pickle on the Christmas tree after the family decorates it. Then, the first child to find the pickle receives an extra present or a special treat. Oddly enough when research was done to discover the origin of this tradition in Germany, most all Germans questioned about the tradition had never heard of it.
no
The Peak
Sometimes people hide toys in the attic when they are intended for a surprise at Christmas or for birthdays. Or, they may put them there to keep them safe for future children or grandchildren.
a coin
In the Attic or Basement
I hide mine at a friends house.
In the doorway