Amy Barclay de Tolly and Peggy Trowbridge of the Home Cooking Guide website offer information on edible flowers including which of the plants are safe to eat.
From the website:
This chart is a collaborative research project by Amy Barclay de Tolly and Home Cooking Guide Peggy Trowbridge. The links will take you to full color photos of the specific flowers to help with identification, but please don't depend solely on these photos. Be sure you know exactly what you choose to consume. If you are allergy-prone, it's probably best to forego consumption of flowers. For more information, refer to the article on Incredible Edible Flowers and Poisonous Plants and Flowers Chart.
• Poisonous Plants and Flowers Chart
• Edible Flowers Information and Recipes
• Herb Information
• Spice Information
• A to Z Recipes and Food