Google Idaho Hunter Jumper Assn and or Boise Saddle and Jump Club. There is a club here, they hold a series of schooling shows locally and do a nice job. Several trainers locally, too, so you would have some options.
There is also the Idaho Dressage and Eventing Association (of which I'm the President), and we have a great time with schooling shows and a derby series each year. Lots of our members cross over to the h/j shows - we are working on our calendar to not have multiple events on the same weekend. Good Luck.
I am on the board for BSJC (previously president, on the board for 6 years, **finally** escaping after this year LOL!!!!).
It's been really quiet the last 2 years, at least in H/J. We canceled both of our larger shows this year due to lack of pre-entry. IHJA shows were moved to Hailey, Idaho. Hoping next year will be better. Seems most are in Dressage/Eventing or western type disciplines as of late.
On that note, are you moving here, and would you like to be on the board for Boise Saddle & Jump Club? We need people!