Yeah, halfway houses and domestic abuse shelters could probably use a ton of pillowcases and larger totes.
If you're affiliated with or doing these classes at a community center that has their 401c, you might be able to ask what that might help you with tax-wise for supplies, or possibly asking for donations (so people know you're legit and not just flipping their donations for money.)
You might also consider running a class on repurposing-- taking "junk" from a thrift store, the trash, a garage sale, your own closets and then what can be done to change it.
I also love the "Saran wrap and duct tape" dressmakers dummies videos on YouTube. I can't pattern see to save my life (I can do okay and then stall on the last 10-20%) but I can do pretty good with fitting sewings. Having a cheap dressmakers dummy that is based off of one's own body (if you do an intermediate or advanced class eventually) is so valuable for visualizing and time management (versus having to check fit with something with a lot of pins in them.)
But as far as a beginner's class, even a hanging sampler of stitches can be a good intro to function and form: