The charitable deduction amount of the flowers is it's estimated fair market value at the time of your donation (the amount you would be able to sell the flowers for).
As for the fees you paid for the delivery costs, it depends. If the shipping/delivery costs you paid went to the charity then yes, you will be able to deduct that amount. If it was a third party delivery service, then you will not be able to deduct those costs. If you are unable to deduct the delivery cost as a charitable donation, you are able to deduct those costs, subject to the 2% of Adjusted Gross Income limit as a miscellaneous itemized deduction on Schedule A (Form 1040).
Also please review IRS – Pub 526 on what is eligible as a
qualified organization for charitable contributions
