Anyone have guesses on what kind of tree this might be from?

[grizz55chev]

Northern Cal black walnut would be my best guess? (and to be fair that's not knowledge, that's leaf ID help). I looked for anything else it might be I was less familiar with cause the leaves are right for some type of walnut but didn't realize the trunks of those Nor Cal black walnuts commonly get 5-6 feet in diameter.

Yep, . That one was over 7' !

 

[dboyd351]

I was going to second Coralillo's guess. Has bipinnate compound leaves, bark looks about right and it gets really big.
Hey Coralillo, weren't you looking for a slab from a tree like that?