I always try to use the local College, most will have a professor with the right knowledge in the biology or horticulture departments and if there isn't one, one of the professors will most likely know of a local expert.
That looks exactly like Ganoderma applanatum- the Artist's Conk or Ancient Ling Chih. I have been harvesting and making a tea from these mushrooms for over 20 years. I have a field test- if the pore layer on the underside is white, scratch it with your fingernail. If it stains dark brown and you can inscribe your initials in it, then you almost certainly have a Ganoderma. The spores should be a brown color, but be careful not to breathe them, because some folks are allergic to the spores. I always dry mine outdoors in the sun, away from the house. The tea has many medicinal properties.
Of course, it's always a good idea for beginners to reconfirm their finds with a local expert before ingesting them, rather than relying solely on internet photos and unknown people.
"In a fruit forest everyone is happy"- Sepp Holzer