MDF (Medium Density Fiberboard) Letters which are readily available at craft stores ranging from 2 inches to 2 feet. These are the larger ones but only run about $3 ea.
Four bunches of Silk Hydrangeas. Available at craft stores as well as large discount retailers and even dollar stores. The quality of the bloom doesn't really matter because you will be gluing them very densely.
Ribbon of your choice, a thicker one is better, about 1.5 inches to 3 inches
Hot glue gun and hot glue
1. Remove all the blossoms from your hydrangea (or whatever flower you choose to use)
2. Warm your hot glue.
3. Start applying dots of hot glue, beginning in one corner and sticking your blossoms as you go along.
4. Go back to fill in any sparse areas with more glue and blossoms.
5. Attach your ribbon to the back with hot glue.