I have what I think are very healthy Oak tres in my new backyard. They have acorn looking fruit and these funny "paper shell" balls with fuzzy stuff inside. It is raining today, but I can send pics. What type of Oak or other tree do I have?

The fuzzy balls on your tree are gauls. They are a reaction by the tree to an insect bite. Many trees have them and they are usually harmless unless the tree is covered with them. Send pics and we will try to ID the tree. Update your profile so we know where you live.
Tony M