Reply by botanist

You’re probably better off not burning it, especially if it contains dust from plywood or mdf. If you know what it contains (i.e. no plywood, mdf, or walnut) you might be able to give it or sell it to a company that grows shiitake mushrooms (the rubbery mushrooms in Chinese food) because they grow on wood or sawdust blocks. Otherwise I would scatter it in some out of the way place on your property. Just make sure not to leave it in a huge pile. I’ve seen lots of huge piles of sawdust in out of the way places in different woodlots from sawmills that closed decades ago. The sawdust will start helping out the next generation of lumber if it’s spread out.