A great place to start is Rebecca Rojer's The World According to Modern Monetary Theory.
For a more comprehensive approach that uses a style compatible with our Getting Money Right, try Warren Mosler's Seven Deadly Innocent Frauds of Economic Policy (pdf).
Bill Mitchell's Billy Blog is comprehensive and thorough, albeit a bit daunting for newbies. Great for reference material and real-world applications to economic policy.
From the UMKC economic department and friends comes New Economic Perspectives, which provides introductory and reference materials. UMKC has long been the hub of MMT research in the US, with Randy Wray, Stephanie Kelton (formerly), Bill Black, and many others. Wray provides the MMT Primer for new students.
The Modern Money Network
aims to bring accurate and accessible knowledge
of monetary and financial systems to the broader public.
You can find video of many MMT luminaries there;
e.g. watch Pavlina Tcherneva promote
the job guarantee.