"TEH iron stone porcelain" usually refers to iron stone porcelain, which is a hard clay and is considered as an excellent raw material for making ceramics. However, this does not determine the age or value of the plate.
"Made in Japan in Matsumura" means that this plate may be made in Japan. However, this is not enough to determine the age or value of the plate.
To determine the age and value of the plate, we need to consider more information, such as the shape, size, pattern, color and manufacturing technology of the plate. In addition, you can consult professional books or professionals to get more accurate information.
Finally, if accurate appraisal is needed, it is recommended that you contact a professional art or antique appraisal institution or company for appraisal.