This is a Japanese pottery tea plate of Hagi Ware made by a famous potter, Seigan Yamane. Beautiful galaxy glaze covers the brown pottery. The seal of the potter is stamped on the bottom.
Seigan Yamane was born in 1952, and started making Hagi ware in 1987. And then, he started his own pottery in 1992 and has ever been awarded a lot of prizes for his great works. The "Sengan Blue" was developed in 2002, and he became famous for it.
(About Hagi ware)