Do companies look at undergrad degrees if you already have a graduate degree?

Yes I always advise that any one moving to higher education academia that it is good to be very versatile in your Academia Institutions - If you are in High School enroll in a neighborhood community college receive your AA degree graduate transfer out of state to a HBCU for your 2 yrs. of Bachelors Degree graduate and apply to a main stream triple AAA seed university and transfer such as Cal tech, New York Univ,University of NC Chapel Hill to receive your Masters Degree and after graduating you want to apply for Doctoral Studies at and Ivy League University such as Brown Univ., Univ. of Penn., Cornell U., Dartmouth U., Yale or Harvard this allows for you to have a diverse academic curricula vitae' and your last phase of academia is your Post Doctoral you would like to be a principle Investigator for such Institutions of research such as world renown Johns Hopkins University or Albert Einstein University and you want to complete 1 community service project overseas for 6 months or 1 year after your Post Doctoral

If the two degrees are in the same field, not so much. It is different if the majors are different. They will look at the undergraduate degree if that is the degree that is related to the job you are applying for.

Psychology is a good background to have if you want to get your masters in social work. I think both degrees will compliment you well when you start looking for jobs in the social work field.

I'll add a third variant answer-it depends on the nature of the degree and how that would also apply to the job at hand. Maybe your psych degree was heavy in use of quantitative measuring and that would be helpful in research work you would do. Or in other instances it could be foundational to your graduate work but not itself interesting. Engineering or math with MBA is cumulatively more interesting for some roles but in others you'd expect a straight path, like accounting and MBA for example.