Hello and welcome!, we are always looking for new acolytes.
Feel free to ask any questions you have.
I would suggest reading these pages. https://www.coreboot.org/Binary_situation https://www.coreboot.org/Board_freedom_levels To clarify a popular misconception most new users have --- coreboot isn't necessarily libre firmware, or even firmware per say (FSP coreboot is simply a wrapper layer that doesn't do much at all)
If you want a *real* coreboot motherboard with native inits: The most popular coreboot mobo is the kgpe-d16, it is the best supported and it doesn't need any binary blobs to work. (but I would get a graphics card because of how crappy the onboard video is) It is a great way to make an affordable gaming PC too (ask me if you want more info, I play the latest games on my KGPE-D16)
I would suggest you buy a KGPE-D16 (SSI-EEB) or a KCMA-D8 (ATX) as I am not sure if the below ones work with the current build, but if you want to do development straight from the get-go more affordable boards are the AM1ML (embedded/HTPC) and the H8SCM (mid range workstation), although they are somewhat blobbed unlike the intel (or new AMD) boards there is no DRM preventing someone from remedying this issue.