→Subscribe for new videos every day! https://www.youtube.com/user/TodayIFound→’s. At this time, coins were actually made of materials that were worth what the coin was worth. For example, a half dollar silver coin contained fifty cents worth of silver. Likewise, a $10 gold coin contained $10 worth of gold. Want the text version?: http://www.todayifoundout.com/index.php/2010/12/why-some-coins-have-ridges/ Sources: http://ask.yahoo.com/20040621.html http://www.bigsiteofamazingfacts.com/why-do-some-coins-have-ridges-around-the-edges