Drop the food item on the crowd and they will automatically accept them.

Round 1:
Crowd: Rice
Groom: Flower

Round 2:
Crowd: Wedding Cake
Bride: Gift

Round 3:
Groom: Present
Bride: Bouquet

Scribblenauts Remix 7-9 Cheats Hints gallery:
7-9-1-a: Do two things to celebrate the newlyweds!
7-9-1-b: What does a bride throw at the end of her wedding?
7-9-1-c: Give them a wedding cake.