I think you should meet with the florist your mom suggests and bring her your ideas to see what she comes up with and what her budget is. Then take your mom with you to meet with two or three vendors whose style is similar to your own.
It’s important that your mom feels that she is part of the process, especially if she’s paying for your wedding. Remember that your wedding day is just as important to her as it is to you.
Once you’ve met with all the possible florists sit down with your mom and go over what each one proposes aesthetically as well as their budget. Review with her why you like or don’t like each one and you may be able to convince her to support your choice of florist.
As the bride you can put your foot down but if mom’s writing the checks this may not go over well. Instead of starting World War III see if you can compromise and hire her florist for another event such as the bridal shower or rehearsal dinner.
And you never know, in the end you may decide that mom’s florist wasn’t such a bad option after all.