So, heads I get. You know, there's a head on it. So when you look at it, you're like "yo! that's a HEAD!" 
But tails?? You're all like, "um...that's a building" or like "um, that's a bird." There's a noticeable absence of any TAILS. 
discus...

I prefer the much more refined Obverse and Reverse when describing a coin.  Heads or Tails is so Farm'y'. 

I’m not trying to be smart here but don’t flying eagle cents have tails

And quarters and almost every denomination at one point at least

Obverse and reverse