Your post lead me to do a bit of online research. Idaho's state flower is Syringa, which is sometimes called Mock Orange. A wild plant expert (who spoke at the local library recently) said it is often confused with Serviceberry. My reading taught me that Serviceberry (also called Juneberry) blooms in March or April and produces berries in June, while Mock Orange blooms May-July. So you are probably right in identifying that plant as Mock Orange.