How about qu … as in clique, pique, picturesque, or toque?
That would be an odd duck spelling that we haven't learned yet.
Also, speaking of qu, for any parents or young children, please do not teach your child that qu says "kwuh". It doesn't. Pretend to say "quit", but then stop before the "it". Voila. You have the sound for qu. Similar to w and y. W does not say "wuh". Pretend you are saying "wet", but stop before the "et". Y doesn't say "yuh", pretend you are saying "yellow", but stop before the "ellow". If you put your hand under your chin, your chin shouldn't drop because you aren't adding a vowel sound.
That's very important when teaching kids to read.
Also, I'm not sure if you could tell, but phonics is my favorite thing to teach. I love it. I'm a total nerd with it. I know random rules such as, singular English words do not end in the letters i, u, v, or j. Except for the words you, thou, and I. There are some more exceptions, but they are words most people will never read, so it's not worth teaching. The vast majority of words follow rules. People were just never taught the rules, so they think they are "rule breakers". For example, "have" has the short a sound, when it should have the long a sound if there's an e at the end. However, the only reason the e is there is because English words can't end in the letter v. So they tack a silent e on. Same with the word live. That's why the words live (short i) and live (long i) are spelled the same.
Told ya. Nerd.