This is a link to what is blooming in July
Native's: https://www.minnesotawildflowers.info/page/whats-blooming/july-native-plants
Non native's: https://www.minnesotawildflowers.info/page/whats-blooming/non-native-species
Not all of these flowers are nectar flowers. Observation is the key. If the bees are working a particular flower they are getting pollen and or nectar from the plant.