Go about 2 mi. Look for a large black pile on the right. There are manypieces of petrified wood on and around this pile. The material is brittlebut almost all have nice side grain and many have nice ring patterns. There are also many large pieces, some too big to reasonably manage.
Thebest pieces are across a wash that runs through the pile.
You can affordto be picky about samples here. Few absndoned store fronts I have yet to find a history for Superior.