Florists - Fall Flowers In Season?

I am getting married in October and want to concentrate MOSTLY on flowers that are in season at that time, but am not really sure which ones those would be (montauk daisies, mums, and what else?)

Also - how does it work when you rent centerpieces (vases and say manzanilla branches) and then your guests take them home thinking they are being offered up? would I be charged for them after the wedding if any get taken?

Thanks!