Since the folder in which Thrifty Thrusday was posted was deleted - no explanation given (since restored but I don't know for how long), I have decided to post all freebies for patterns in their repective folders. Given, however, the difficulty in keeping threads organized with long sequences of posts, I will attempt the same thing here I am doing with weekly tips and tutorials ---a single, edited post for each main category. If a post is especially long, I will stop it at the calendar quarter and start a new one, and, in teh interest of my own time, I am only going to recover freebies from 2013 on fmor the old Thrifty Thursday Threads... ALso, when a post gets toolong, which is likely for both knitting adn crochet patterns, I will break them up into quarterly lists...
In the past, if my memory serves me correctly --- the main freebie categories for yarn were knitting and crochet patterns and downloadble eBooks; categories like felting, tatting, weaving, latch hooking and macrame have their own threads in this folder and freebies have been posted ther in teh past. So this thread will have, at a minimum, those three posts to this OP... I will add more if needed as I become aware of more freebie links.
Some yarn manufacturers and sellers also have archived free patterns, often mixed knitting and croceht patterns, in their archive. Here is a list of those... as I run across them
Patons has free patterns here: http://www.patonsyarns.com/search.php 
Bernat maintains a large knitting and crochet patterns archive: http://www.bernat.com/pattern.php 
Herrschners maintains an archive with miscellaneous projects, including knitting adn crochet: http://www.herrschners.com/freeprojects.aspx 
Hobby Lobby has a "Project Inspriation" page that features needleart and wearable projects as well as other categories that may also have yarn features: http://www.hobbylobby.com/project_inspiration/projects/projects_by_category_landing.cfm?menu=4 
Michaels also has a projects page which includes yarn and needlecrafts: http://www.michaels.com/Yarn-Needle-Crafts/projects-yarnandneedlecrafts,default,sc.html