The flowers are 'champak' and they are blooming in Goa right now. You can find them by following their sweet smell in the markets or on road-sides where village women have strung them into gorgeous 'venis', little garlands designed to decorate one's hair.
The botanical name of the plant is 'Michelia champaca' and it is a variety of the Magnolia family.
Interestingly, I found a video that shows how to string flowers together in a veni using two long threads and stringing each flower using special knots. I don't think the video explains enough for one to try this on their own but clearly shows how delicate the process is. Click here for link.
The strong sweet smell, vibrant yellow color and delicate shape are a treat for all senses.
And did I tell you that they smell like heaven... the entire house smells like a perfume factory !