Question
We have a tree in our back yard in Covington, GA which has baseball size green "fruit" which looks like a human brain.  The leaves of the tree are small.  We cut open the "fruit" and it has white liquid inside.  It is not very appetizing to look at and the "fruit" is not very pretty either.  The balls have been green all summer and continue to be green now that Fall has started.  Any ideas?

Answer
These are osage orange a member of the mulberry family.

Osage-orange (Maclura pomifera) produces no sawtimber, pulpwood, or utility poles, but it has been planted in greater numbers than almost any other tree species in North America. Known also as hedge, hedge-apple, bodark, bois-d'arc, bowwood, and naranjo chino, it made agricultural settlement of the prairies possible (though not profitable), led directly to the invention of barbed wire, and then provided most of the posts for the wire that fenced the West. The heartwood, bark, and roots contain many extractives of actual and potential value in food processing, pesticide manufacturing, and dyemaking. Osage-orange is used in landscape design, being picturesque rather than beautiful, and possessing strong form, texture, and character.

Osage-orange has been planted in great numbers, first as a field hedge, before barbed wire became available, secondly as a windbreak and component of shelterbelts, and thirdly to stabilize soils and control erosion.

Osage-orange heartwood is the most decay-resistant of all North American timbers and is immune to termites. The outer layer of sapwood is very thin; consequently, even small-diameter stems give long service as stakes and posts (40,43). About 3 million posts were sold annually in Kansas during the early 1970's. The branch wood was used by the Osage Indians for making bows and is still recommended by some archers today.




Here is a web link to some history of this tree if you are interested.
http://mdc.mo.gov/conmag/1995/11/06.html