I have pieces of blue & white dinnerware with a pattern that looks like "Blue Onion" but it only says JAPAN on the bottom. Can't identify?

Hi, grammaleigh!

Would you please explain what you mean by "Blue Onion"? Is this china or something else, please? Also, would you be able to post some images of what you have, please?

Just a thought, but if what you have isn't numbered and/or marked in any way, then it's probably something that is mass produced that probably also is not worth all that much monetarily.

Thanks!