Peanut wood is a variety of petrified wood, where the shape and structure of the wood is preserved when the original organic material is replaced by minerals. The mineral composition is chalcedony or jasper (i.e., silicon dioxide), and the petrified wood has the hardness and durability of quartz. Peanut wood is not actually from the peanut tree, since peanuts don't grow on trees. But the lighter colored sections of the petrified wood was thought to be the color of peanuts.
I love GemSelect, personally. I browse their site almost daily to see all the new stones available. Their selection is pretty amazing. The quality isn't always the highest and the cut of the stones isn't always perfect. But for the price, and if you look hard enough, you can find a real gem, so to speak.