Here's why:
* Subject Pronoun: "I" is a subject pronoun, used when the pronoun is performing the action of the verb.
* Object Pronoun: "Me" is an object pronoun, used when the pronoun is receiving the action of the verb.
In the phrase "my mother and me," the pronoun is part of the subject of the sentence. For example:
* My mother and I went to the store. (Correct)
* My mother and me went to the store. (Incorrect)
You can always test this by removing the "my mother" part of the phrase. Would you say "I went to the store" or "Me went to the store?"