You can also choose flowers that help you out in the garden. Plant Calendula officinalisas (marigolds) around your tomatoes to deter aphids. The orange petals have a peppery flavour and can be used as a cheap alternative to saffron in the kitchen.
Nasturtiums have edible leaves and petals too, but unlike marigolds they attract aphids, as well as cabbage white butterflies. Plant them near vulnerable veg like kale, beans, cabbage and cauliflower, and the pests will eat the nasturtiums instead of your crops.