Oak galls, what are these balls on my tree. Gall wasp

What are these balls on my tree, oak galls. The gall wasp is a insect that causes abnormal growths on various tree species. There are citrus galls. How to treat citrus galls, what are these balls on my tree. Growths on trees. Growths on leaves.
How to treat gall wasp.

[alexdobo]

the what color is the gall and what species is the tree? where are you from?

[sus]

Please can you tell me where to find these oak galls in which stores I need them for medical reason, thanks.