I lost a colony of bees to starvation this fall as there are very few pollen producing plants or flowers after July. I'm looking for a wildflower mix to grow in a meadow to provide late season pollen for the bees. The flowers should be drought tolerant as the only water will be rainfall and do well in sun. Any suggestions?

You don't say what zone you are in, but asters are a good late bloomer. Curly cup gumweed(Grindelia squarrosa), which is a weed as its name implies is an excellent late blooming flower for bees. I don't know how much pollen they gather from it, but the honey is excellent though slightly darker than alfalfa honey.
Liatris and goldenrod are also good late bloomers though I'm not sure how much bees utilize them.