There are many edible flowers, and whole books are devoted to the subject. These are just a few. Some people may have allergies of which they were unaware, so some caution should be taken when trying new or unusual foods.
Dried roses, chrysanthemums, bergamot, clover, plum blossoms make good teas, alone, mixed with other herbs or with black tea. I've also heard of but have not tried violets, linden flowers, marigolds, peonies, goldenrod, hollyhocks, camelias.
Nasturtium flowers are excellent in salads. They taste like watercress or radishes. Different colored flowers have different flavors. Some are quite hot, similar to horseradish.
Other flowers for salads that I haven't tried yet: tuberous begonias, borage, calendula, carnations, chrysanthemums, English daisies, dianthus, fuchsias, geraniums, gladiolas, hollyhocks, Johnny-jump-ups, lavender, marigolds, pansies, periwinkles, roses, stocks, violas, wisteria.
Day lilies look nice in salads but are kind of bland, like iceberg lettuce. Lily pods are good mixed with other vegetables in stir-fry or stews. Squash blossoms and buds can be used similarly.