The question from the above post comes to us today from Google. Someone Duluth, Minnesota, typed it in, and they got my blog.
However, in an effort to fully serve my readers, I'll answer the question.
To my knowledge, the only uniquely Mormon Holiday is the day the pioneers entered the Salt Lake Valley. Since this holiday is celebrated when most schools are on summer break, it's a moot point.
So, the answer is no.
Do you have any more pressing questions to ask me? I'm not an expert, but I play one on the internet.... Leave a question in the comments section, and I'll answer them.