The Oak seed is a seed that grows into an Oak Tree, which is a tree that grows acorns.

The oak tree will grow acorns and attract eaglairs.

(The above additions about the Oak Tree is not neccessarily the case. The above mentioned statements were this Viva Pinata's player's experience. My experience with the game in August 2011, was that I got the Eglairs attraction before I ever received the Oak Tree Seed from Seedos. And as I was reading tips and tricks for the game, I came across another wiki contribution stating that Seedos gives several other types of seeds that I have yet to receive from him. I do think that conditions will vary dependent upon each player's experiences in the game. Also, some of the pinatas can not be attracted until you reach certain levels in the game. -another wiki contributer) You can also buy the mine at level 26 for 16,500cc when you have diggerling he will sometimes find oak tree seeds and be warned, plant in an open area!