Light's Death Note burial site is where Light Yagami buries the Death Note to fool L into thinking he has no evidence to prove he is not Kira. After Misa follows instructions Light gives to her, she goes to a forest where Light buried a Death Note. Misa digs up the Death Note in the forest and finds the Death Note, regaining her memories of using it when she holds it. Inside the Death Note, she also finds a letter from Light addressed to her instructing her on what to do next.
The burial site is located within an unspecified forest.
Not much of the forest is actually seen, but the burial site does seem to be in a sizable open area within multiple trees covered in a lot of fog.
The Death Note was concealed inside a box, which Misa dug up and regained her memories.