The blooms ARE edible for sure, as I have done so myself. They have the taste of fresh spring peas, and are lovely in salads.
just make sure that you know where the blooms came from, and that nothing has been sprayed nearby. Also, collecting edibles from along the roadside is not advised because of the exhaust from the vehicles will make an invisible coating on whatever you harvest. As with all wild edibles, when in doubt...don't.
I look forward every year to a spring salad with redbud flowers and purple wild violet flowers torn up and sprinkled on top. I found out that redbuds are edible from a sign in the San Antonio botanical garden which claimed the early pioneers planted them as food crop plants. It said you could eat the flowers and the pods, while they were still very small and tender. The flowers have a light lemony flavor which is delightful, but I've never tried the pods.