I know some of the locations that I'll share below
1. You can find a couple of them in the Forbidden Forest
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2. then there are more right below The DIM FOREST under Giant Banyan.
3. To the right of Giant Banyan
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4. There are more to the top left of giant banyan.
Just keep exploring around this region around Giant Banyan and you'll find plenty of Coriolus to find. Hope this helps