Google! (try "Data csv on xxx", like "Data tables csv on MLB statistics")
Free online data repositories
Open Science Framework (search for publications, then find their data available on OSF)
Government agencies (see below)
Major research NGOs (e.g., Pew Center, the World Value Project)
All government data
Population ---> use the census data
Health Statistics
Health Behaviors
Health Care Utilization
Medical Expenditure Panel Survey (e.g., mental health service use)
Crime Statistics
Burns Institute: https://data.burnsinstitute.org/
Media consumption