If your radishes are flowering, it is likely that they have gone to seed, also known as bolting, and have begun growing as any other plant would. Many vegetables and herbs tend do this because of hot weather.
If radishes are planted in the summer or late spring, they are very likely to bolt and grow to flower. After they have gone to seed, radishes become practically inedible. The become bitter and often take on a woody taste and texture. It's possible to stop this from happening, or at least discourage it, by keeping the radishes in cool, moist conditions.