In Spain, seta is a very common word for mushroom, especially one growing in the wild.
Hongo is broader and more scientific. A native speaker in everyday conversation is very likely to say seta if they mean a mushroom you see outdoors.
Also, seta is feminine, which matters later for la.
Junto a means next to, beside, or right by.
So:
A very similar expression is al lado de:
Both are natural. Junto a is just a bit more compact.
Dijo que means said that.
It introduces reported speech or a reported idea:
Spanish often uses decir que to report what someone said, thought, ordered, suggested, etc., depending on the context.
Here, it is not just neutral reporting. Because what follows is no la tocáramos, it sounds like your mother gave an instruction or warning.
Tocáramos is the imperfect subjunctive of tocar.
It appears because after a past verb like dijo, Spanish often uses the subjunctive when reporting:
Here the idea is:
That kind of reported instruction normally triggers the subjunctive.
By contrast:
Neither fits the meaning of a reported warning.
Both structures are possible, but they are used differently.
This is a full reported clause: my mother said that we shouldn’t touch it.
However, dijo que no la tocáramos is very natural when reporting a negative instruction in a complete sentence.
Also, adding nos would make the target clearer:
But Spanish often leaves nos out if it is obvious from context.
That makes sense because:
So:
Even though piedra is also feminine, the likely meaning is that the mother warned them not to touch the mushroom, not the stone. Context tells you which noun la points to.
Because here the verb is a finite verb form: tocáramos.
In Spanish, object pronouns usually go:
So in this sentence, la tocáramos is the correct pattern.
Yes. Both are correct imperfect subjunctive forms:
In modern Spanish, both are grammatical and common. In many contexts, -ra forms like tocáramos are more frequent in everyday speech, but tocásemos would sound perfectly natural too.
So:
Both mean the same thing here.
Because una seta is a thing, not a specific person.
The personal a is used mainly with direct objects that are:
So:
But you would say:
because mi madre is a person.
Both are possible.
Adding nos makes the indirect object clear. Leaving it out is normal if it is already understood.
The accent shows the correct stress.
Without the written accent, the word would not follow normal stress rules for that verb form. Spanish uses accent marks to show pronunciation and sometimes to distinguish forms clearly.
So:
It comes from the verb tocar, and the accent helps mark the stress on cá.
Yes, that is a very literal way to see the structure:
But natural English usually changes that into:
This is a good example of where Spanish uses a subjunctive clause and English prefers a different structure.