(I don't know what works and what doesn't so I will list them all)

Teleflora
PJ15 - save 15% on everything
PEEPED - $10 off any bouquet
9CM25 - 25% off
9EA20A - 20% off

1-800-FLOWERS
BUNNY2 - 20% off
MARTHA45 - 10% off
SPR9 - $5 off

FTD
11967 - $15 off
5658 - 25% off when you use AMEX
13131 - $15 off any order