Ingestion of ripe Frangula californica berries causes nausea and vomiting, although there are claims that the berries and seeds are safe and edible. The seeds inside the berries have been used to make coffee substitute. Although the plant itself looks much like a coffee plant, its berries, which are succulent, do not.
Coffee beans have been eaten for hundreds of years or more. As such, it is best to eat coffee beans in moderation. That said, green coffee beans — which are raw — aren't very pleasant to eat. They have a bitter, woody flavor and can be hard to chew.