Simplify the following text for a Grade 8 native English-speaking person.
Original: In some Arthurian literature Glastonbury is identified with the legendary island of Avalon . Joseph is said to have arrived in Glastonbury and stuck his staff into the ground , when it flowered miraculously into the Glastonbury Thorn .
Simplified: It is well-known for the Glastonbury Festival which happens every year in Glastonbury .