Will this clash? Hair and flowers..

I don’t think so. It’s going to play well with the flowers.

I think it’ll be fine together

I think it’ll go well together.

I think it'll be lovely together

I don't think it will clash, but if you wanted to tie some of the colors of your bouquet into your hair, you could ask your florist to give you a few extra of the smaller, more colorful flowers (or berries if you're using any) and add one or two stems to your hair.
I was thinking of either berries or some of the tiny blue flowers from mine but I don't know what anything's called, so here's a very zoomed in picture.

I definitely don't think they'll clash!

You could also take a look at some of the colorful floral hair pins on Etsy if you want more color in your hairstyle!

It looks nice. One piece of advice I'm happy I followed - this is the (only, IMO) time to use faux over real flowers. I'm allllll for real flowers, but in your hair after a full day they get stinky and lifeless and a sticky mess. Etsy has some really pretty options.

View Quoted Comment Good point! I was originally thinking real flowers but then thought fake or dried flowers might be better because I could use them in my trial and see exactly how they look. The ones I was looking at on Etsy are dried so I think I might go those. Thanks all for the advice!

I don't think your hair pins and flowers need to match at all. You can do a nice jeweled, beaded, or pearl hair piece and have bold flowers if you want to.