I'd say it was agatized petrified wood. Nice stuff too. It'd make somebody doing lapidary work real happy, and it'd make some real nice points too. The right combination of minerals and it could be opalized.
Your county has lots of petrified Palm wood although yours does not appear to be Palm. Sill thinking petrified wood but what mineral it was replaced with is unknown to me. Call Hal. He knows every rock in the state. In person ! Hal?
I found that one 4" blade out of palm and a couple of others out of wood, those though were of much lower quality. The pieces of palm that I've found were generally small but of high quality. The other wood was fractured and had a lot of inclusions.