Yes, it is great fun to try and grow fruit from produce but be warned that  not all seeds create new plants that are just like the mother plants. Many are hybrids as I suspect the watermelon may be. This means they do not breed true so you may find you have different varieties of melons or even seeds that do not sprout at all. Gardening is an adventure so dig in ang give it a try. Keep growing, Marianne Binetti