the thing w there being potatoes in lord of the things is that there ARE actually at least 2 built in explanations for it:
1: they don't have potatoes; the references to potatoes in the Shire were added by Tolkien-the-translator as part of a wider localisation. when Sam mentions potatoes he's actually talking about some other vegetable
2: given that Middle Earth was historically ruled over by the Numenoreans who come from a lost kingdom on the other side of the western ocean, it could be that Numenor was in or had contact with ancient America and brought potatoes back with them
2 is kind of a stretch tho interesting to contemplate; 1 however on some level i think is the correct answer. the Shire's resemblance to England is 100% canonically a localisation thing. The Shire is England bcos it's the main characters' home and the intended audience of the book was English people.
the decision to incorporate post-colombian exchange plants like potatoes and tobacco isn't innocuous but it was a purposeful decision with reasoning behind it beyond 'they have potatoes because I said so'.
lord of the rings adaptation where Sam is talking about how much he loves potatoes while holding a vegetable that is visibly not a potato, a la pokemon characters talking about jelly donuts while eating rice balls
just bringing this back for no particular reason to clarify:
the point i was gesturing at in the OP is that sometimes in LOTR Tolkien did stuff For A Reason (in this case a bad, racist reason) and subsequent fantasy authors picked it up and ran with it without thinking through the implications so now it's just a Thing in fantasy literature even tho most writers aren't trying to do the specific thing Tolkien was doing (create a world that's evocative of mid 20th century England) so in addition to be vaguely racist its also kind of incoherent.
