My   stones that I collected, mostly Texas Agate and petrified
wood but also some paint rock agate from Alabama, too.  
These were initially tumbled in a lortone QT12 and then
finished in an ultra-vibe  UV-10 vibratory tumbler with cerium
oxide .
Petrified wood from Tilden, Texas
The close-up photo shows the
grain structure as well as the
hollow tubes. I believe this is
"grapevine" which is similar to
palm wood except the tubes are
much smaller.

Lower right is tumbled Alabama
Paint Rock Agate.
Go to the main DIG FOR CRYSTALS site   
Agate from Zapata Texas and also some strange agate from Marfa, Texas (
very close to Alpine).
The agate nodules at Woodward Ranch in
Alpine, Texas are called "biscuits".     No two
are ever alike and some are quite nice!
Texas Agates tumbled
woodward ranch - biscuit
agate from bobs nob on falcon lake in zapata texas
petrified wood from Tilden , Texas
Agate from marfa texas
paint rock agate