I'd recommend composting any sawdust/shavings first before including them your garden.
As has been said already, no black walnut or anything really exotic.
I make sure to compost mine with a healthy mix of browns and greens.
The wood dust/shavings are the brown, grass and leafy trimmings are the greens.
We are kind of composting nuts. It's just so easy to do and good for the garden. It's really as easy as mixing brown and green and putting in a pile on the ground. Wet it down and watch it go. It should heat up real good at first, and eventually it will become dirt. If your patient enough, at some point the worms will get in it and then you know it's good to go...
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