What is the reason for her to not let you use henna?
I was taught the absolutely WRONG thing when I got into the hair business. There were a lot of imported brands of henna which actually were not 100% real henna. They were marketed as brown or black or even blonde henna. These hair colours had the worst possible metallic dyes in them. Some so bad they are very carcinogenic and allergy inducing. When you permed or coloured over these 'hennas' you ended up with a horrible mess of green hair. . Henna got a hugely bad rep because of these companies that used the word 'henna' when it wasn't real henna in the first place.
So.... If your mom, like me, believes henna to be the devil's brew, and this is the reason she does not want you to use it, you need to help to educate her. Educate yourself first here:
Henna for Hair
There's a great little pdf 'book' you can download for free and get all the information you need to tell your mom. Maybe you can get her to read it, too.
I found out through this site all about henna and it's been wonderful for my hair. It's not perfect for absolutely everyone, but most will have great results. It really depends on what you are starting with and where you want to go.
Henna can only add colour, it cannot lighten. It can only be red. You can add indigo (also natural) to make brown. It gets more complicated if you need to do this, but it can be done. If you are putting henna on blonde hair, the result will be very intense, like it is in my avatar. If you put it on brown hair, you will see a nice copper glow. The shine is amazing.
I wish I had known the truth about henna 30 years ago.. I have wasted a lifetime of gorgeous curls because colouring them with permanent colour made them look so damaged. I wish I could go back and do my own research and not believe that person who misinformed me! Heck, not only that, I think of all the money I wasted on chemical colours.. and all the pollution caused by it! It's sad, really!!!