below, from left to right: black walnut, white oak, cherry, maple

http://dmdm.us/files/gimgs/th-40_walnutsample.jpg
http://dmdm.us/files/gimgs/th-40_wood1.jpg
http://dmdm.us/files/gimgs/th-40_wood4.jpg
http://dmdm.us/files/gimgs/th-40_maple.jpg