I went out to Arizona this fall. Still looking for mammoth, but did come back with triassic petrified wood. The Petrified Forest is outside of Holbrook. It really is a whole petrified forest that was brought down by massive floods-- whole trees no branches no leaves. After that i went looking for wood i could take home. Near the Petrified forest is a paid dig site DoBell ranch. It looks like something out of "American Picker " with the old trucks and and the old buildings. There were visitors there who went to town digging. I stayed with surface finds and and came home with more wood than I know what to do with-- in great colors.