Originally from Africa or India, hibiscus flowers arrived in Mexico in colonial times and have become deeply integrated into Mexican cuisine. Often used to prepare agua de jamaica, or freshly flavored water, fruit popsicles or Jell-O, the dried flowers infuse the liquid with a deep, vivid red color.
They are not just any Hibiscus flower though. These are "Hibiscus Sabdariffa" also known as Roselle. In Mexico known as Jamaica, it is well known in Mexico that the flowers contain helpful diuretic and digestive properties, as well as high levels of vitamin C and other minerals. These days it is easy to get them in many stores in the US or online. They can be incorporated into many other dishes to add a peculiarly tangy taste, similar to cranberries (continue for more information and photo).
When I was younger I used to enjoy playing with the flowers and pretending to make magical potions in my family's kitchen. Now that I am grown up, I keep on playing with them in my own kitchen! More modern takes of Jamaica include it in sauces for meats, vinaigrettes for salads and different kinds of desserts.
Here is a photo of them in my backyard...