Assuming you were born in the United States, your original birth certificate is on file at a state. county, or local registrar’s office. Your mother, at most, has a certified copy. You can order your own certified copy, usually for around $5 to $20 which is just as good as her certified copy.
If you were born outside of the United States or your birth was not registered or some other unusual circumstances surround your birth, then your mother might have an original or hard-to-find document that you might need someday.
If you are in the United States, when you apply for Social Security or Medicare benefits, they are going to want to see your birth certificate (or some other combination of funky old documents). If you ever move out of state, they are probably going to want to see it to issue you a new drivers license or state ID card. And you will need one to get a US passport.
I know it seems silly, but with all the political hysteria about illegal aliens, a birth certificate is becoming a nuisance that you have to deal with and I’m sure that as time passes it will be required in more and more places.
Your mother might also have other papers. For example, if you are Catholic and want to be married in a Church, it would be handy to have your baptismal certificate.
Oops I’m sorry I missed the part about your being born in another country.
It might not be easy to find the right place to get a copy if you need it in the future, depending on the government bureaucracy that’s in place where you were born.