Agatized wood!

This rock appears to be agatized wood, also known as petrified wood with agate.
Here's why:
* Wood Grain Presence: You can still see the distinct wood grain structure, indicating it was once wood.
* Agate Inclusions: The darker, bubbly or layered formations within the wood grain are likely agate. Agate is a type of chalcedony (a form of quartz) that often fills voids and replaces organic material in petrified wood.
* Color Variation: The mix of earthy tones (browns, tans, creams) along with the darker, more translucent areas (likely the agate) is typical of agatized wood.
Agatized wood is a fascinating combination of fossilized wood and agate, making it a popular material for collectors and lapidary artists.