In semiarid regions of Mexico, it is common to use the floristic richness of wild plants as food ingredients. Hence, flowers of Agave salmiana, Aloe vera, Erythrina americana, and Myrtillocactus geometrizans, which are typical and traditionally consumed flowers, were analyzed. The physicochemical properties; proximate composition; the contents of minerals, carotenoids, ascorbic acid, phenols, and total flavonoids; the quantification of phenolic compounds by HPLC; and the antioxidant activity in vitro were determined. The flowers were high in carbohydrates, proteins and minerals, mainly K and N in flowers from E. americana and M. geometrizans, respectively. The highest concentration of carotenoids was detected in red flowers (E. americana). Total phenols ranged from 4.73 to 72.40 mg of gallic acid equivalents per gram of dry weight (GAE/g DW). However, the highest value of antioxidant activity was 819.80 μmol of Trolox equivalents per gram of dry weight (TE/g DW). The highest values of phenolic compounds content and antioxidant activity were found in the flowers of M. geometrizans. The antioxidant activity of flowers was mainly related to phenolic compounds. The main phenolic compounds detected in flowers were rutin and phloridzin. The edible flowers analyzed in this study are a potential source of compounds with high biological activity.