I would recommending looking at school-specific scholarships as well as non-profit granted scholarships. For example, my alma mater (University of Southern California) offers merit-based scholarships if you apply by the early deadline (Dec 1). USC offers great STEM majors, I studied engineering and had a great experience.
I offer two additional sources for learning where there are good scholarships in STEM fields. 1)Local high schools and their guidance counselors 2)Local newspapers that advertise scholarships that have been awarded to students. For this one, it would require paying attention to such announcements about a year or two before you start to apply so that you have a sense of what is being awarded, by what person or group and on average, how much the award is.
Hope you find this answer helpful and best of luck to you!