ePub Sources

Standard Ebooks (US)

https://standardebooks.org/ "...a volunteer-driven project that produces new editions of public domain ebooks that are lovingly formatted, open source, free of U.S. copyright restrictions, and free of cost."

Faded Page (Canada)

https://www.fadedpage.com/index.php "These books are public domain in Canada (because we follow the Canadian copyright laws)," Distributed Proofreaders Canada (DPC) publish here (and also some to Gutenberg etc)

Global Grey (UK)

https://www.globalgreyebooks.com/index.html
"My name's Julie and I've been running this site for around twelve years. I format all the ebooks myself, as well as maintaining the website. This is an ongoing project that was born from a love of reading and a commitment to make free ebooks that look good."

Project Gutenberg Australia

https://gutenberg.net.au/

Roy Glashan's Library (Australia)

https://freeread.com.au/
"This library gives readers access to a selection of free e-books hosted at two web sites—Roy Glashan's Library (RGL, formerly Freeread) and Project Gutenberg Australia (PGA)"

Others

Internet Archive

Can be hit and miss and they seem to be OCR only (not manually cleaned up, like the above)