Beginner needing help to ID fungus

Beginner needing help to ID fungus

Observation - Beginner needing help to ID fungus. Description: There was quite a few of these large-ish fungi in an Oak woodland. This one was about 20cm in diameter. Hope someone can help!

There was quite a few of these large-ish fungi in an Oak woodland. This one was about 20cm in diameter. Hope someone can help!