Even if I've never mentioned it on this website, I have suggested on my own site (the Quiz Monkey) that if asking about anniversary gifts, you should specify which list you're referring to – and also, preferably, your source.
Wikipedia gives "Traditional US", "Traditional UK" and "Modern" lists, as well as lists for flower gifts and gemstone gifts. On the Quiz Monkey I compare these with other lists from the Infoplease website and Pears Cyclopaedia.
The 20th anniversary is at least one where all sources seem to agree that the traditional gift is China.
© Macclesfield Quiz League 2019