Gartner: E-learning Market Pushing Toward Open Source
Interview on the increase of open source LMSs Moodle and Sakai in higher education
pipwerks » Not so crazy about Moodle? Try Chamilo
Another open source LMS option forked from Dokeos called Chamilo
eFront: Top 10 Open Source e-Learning Projects to Watch for 2011
Great collection of open source e-learning projects and tools, including multimedia development, screen recording, Android app development, an LMS, and more. (Technically, some of these are Free, not Open Source, but still a valuable list.)
A Guide to K-12 Open Source LMS Options -- THE Journal
Overview of open source LMS options with examples of districts currently using them. This article covers Moodle, Sakai, Canvas, OLAT, ATutor, and Google CloudCourse. I thought CloudCourse was owned by Google, but it appears the code has an Apache license. CloudCourse seems to be mostly scheduling rather than a full-fledged LMS.
Free Open Source LMSs are like Puzzles « E-Learning 24/7 Blog
Nice metaphor for working with free LMSs. Moodle can work "out of the box" for some small instances with limited needs but this description is a fairly typical experience of customization.
Totara vs Moodle - Moodle For BusinesseseLearning Experts | Paradiso Solutions
Screenshots and overview of Totara's features that can make it a better fit for businesses than default Moodle.
Jennifer Valley: Free (or Cheaper) Tool and Resources for eLearning (February 2015)
Inexpensive or free tools and resources for animation, audio, graphics, course development, and more
The Top 8 Free/Open Source LMSs - Capterra Blog
This is actually 18+ free and/or open source LMSs. Some are truly open source, some are freemium or other business models. If you want a list that goes well beyond Moodle and Canvas, this is a good place to start.