If you're looking for some free homeschooling textbooks, I've found some great ones for math and science.
These math and science textbooks are available for grades K-5.
Specifically, the math texts are for first grade through fifth grade. There are also online math activities suitable for Kindergarten through fifth grade. Kids love to play games online (or at least mine do)and the ones available on this site are fun and engaging.
For older kids, there are Algebra I, Algebra II and Geometry Books. I wish I had known about this last year when my oldest was learning Geometry!!
There are also science textbooks for first through fifth grade, and science fun for Kindergarten through fifth grade.
Enjoy! :-)