I want to get another bird but my mum says no, what should I do?

Get a fake one that looks real, bring it back, and see how your parents react. If they accept, replace plastic bird with real bird. They'll never know the difference.

Haha, I had one bird and wanted another too. I just went out and bought another, it took my parents a whole month to find out I had another budgie. Luckily my parents didn't make me get rid of him although they were pretty angry.
I suggest you just go out and get another.

Get one anyways, what is she going to do? Worse comes to worse you get yelled at and she takes it back to the store. I wanted another guinea pig and my mom said no but I got one anyways and she got mad and yelled at me but didn't take it away or anything. She let me keep it and wound up loving it. Just have to deal with getting yelled at

Get a small radio and turn it on quietly during the day in your room while you are at school. The bird will enjoy it's programming and be ready to greet you when you are home as well. Most toy birds made for kids can't actually do much and requires you to push it's buttons, your real bird can get territorial over one made for birds and become a little nippy around one... a problem you'll not have with the radio tunes.

If you spend time with your bird everyday, or nearly everyday then your bird will be fine.

Grow up and accept the fact that you're not getting another bird.