Below are ten free websites for graphic designers that provide resources such as fonts, photos, and mockups. These websites offer resources that are for both personal and commercial use. I recommend using resources that are for commercial use, especially for freelancers. In a scenario when a client, you are only allowed to use resources that can be used for commercial use unless the designer/photographer says otherwise. Using commercial use resources for business use puts designers less at risk because they have to worry about copyright infringement. Here are the resources that I highly recommend:
Unsplash is a website shares stock photographs with 207,000 photographers and 17 billion photo impressions per month. All of their photos are for commercial use with a contribution to the photographer (recommended).
Pexels is another website that shares stock images for commercial use with a contribution to the photographer.
Burst is also the same as pexels and unsplash with providing free stock images its essential to have multiple sites to look at to compare different photos to others.
For Fonts
Font Squirrel provides 100% free fonts, which you can download straight to your computer.
1001 Fonts provides 100% free fonts for commercial and personal use, which you can download straight to your computer.
https://www.1001fonts.com/free-fonts-for-commercial-use.html
Font Space provides legally licensed fonts, and according to their website is "The best place in the universe to search for amazing fonts."
https://www.fontspace.com/category/space
Dafont has 70000 free fonts download that is for both personal and commercial.
Mockups Design is a site where you can find free premium mockups in private and commercial work
Mockupworld creates PSD mockups that are easy to use in projects, app showcases, and presentations.
Anthony Boyd Graphics provides high-Quality Mockups and Textures for graphic designers, which center mainly for branding design.
https://www.anthonyboyd.graphics/mockups/