She can look at/discuss different hairstyles, help u find your jewellery, go shoe shopping with you, etc.
You could also talk to her about different centrepiece and bonbonierre ideas too.
If you're making your own invites she could help with that (or if you're getting them made u could ask her opinion about the design)
I also took my mum to the florist with me and she helped me pick flowers i liked.
There's plenty of ways to involve her!