Balloons with photos of memories tied to the bottom is a sentimental and thoughtful proposal idea. Let her pop all of the balloons to find the ring. You can fill the rest of the balloons with sweets, glitter or flowers.
Give to guests or to arrange them on tables or pews, here's my custom cases to put around tissue paper, kraft paper. So you can add a decorative touch to your handkerchiefs. A circle can hold 3 handkerchiefs.