There are four different photographs here, taken at two different spots in the City of Waltham. The tulips were growing in beds planted and maintained by the City. I suspect all came originally from the same batch of bulbs.
The sky was overcast, brightly, when I took these photos. There were no intense shafts of sunlight to set these blooms ablaze. The glow you see came from the flowers themselves, bathed in the bright, soft light.