As almost everyone's said - native speakers would say "Mary's going to the story with us." or "We're going to the store with Mary." (Or, "Mary's going to the store with them." or "They're going to the store with Mary.") depending on who is initiating the trip to the store. "Mary and we" doesn't really make sense. Mary would be part of "we," so why not just say "we"? ("Mary and they" has a similar issue, why not just "they"?) If you do, for whatever reason, need Mary to be distinct from the rest of the "we" or "they," then someone will need to be distincted out of the subject of the sentence.

Hi Igor, From my experience, we don't usually say "(person) and we" or "(person) and they." In situations like these, it's more typical for us to say "(person) is (action) with us" or "(person) is (action) with them." For anyone who is curious about the grammar when it comes to these types of sentences: the trick is to take the other person out of the sentence to see if it makes sense with the remaining pronoun... 1) Mary and us are going to the store. --> Us are going to the store. (Obviously incorrect) 2) Mary and them are going to the store. --> Them are going to the store. (Obviously incorrect)

Hello Igor, To refer your question, it is quite interesting. To me, I would like to vote the correct sentences as below: - Mary and we are going to the store. - Mary and they are going to the store. To refer these sentences, in the beginning of sentences, both are used in a kind of subject form which is called "Compound Subject". In my opinion, in general, most of people (including myself, but I mainly made mistakes when I was young) are not familiar with this kind of grammar constructure of subject form , e.g.: Mary and "we " or "they". Due to this situation, people are used to build up a sentence with using a subject (E.g.: Mary) / subject pronoun (e.g.:"we" or "they") plus an object pronoun (e.g.: "us" or "them") to be combined together when they need to figure out the sentences. I hope it can help you!

No native speaker would say either of those options. What some people do however in speech, myself included at times, is replace 'I' with 'me.' It's using an indirect object pronoun as a direct object pronoun so not strictly correct but plenty of people do it. A lot of the time it is more idiomatic. Mary and me/Me and Mary are going to the store. The correct sentence is 'Mary and I are going to the store.' (Always in that order, it sounds horrible to say 'I and Mary...'

The "vox populi" as you put it, is a Latin phrase that is in the English lexicon, but it is so rare that no one would understand it. It's in the same category as "in loco parentis", a teacher might understand it, because that is what they are, but no one else will. All the phrases you used are not standard usage. "We are going to the store with Mary." "They are going to the store with Mary." That is the standard usage. Some of what you wrote is grammatically correct, but why use it if it is not standard usage? It sounds foreign...