SocialNature currently has 40+ free trials you can apply for! After creating an account, simply head to their Products page and make sure to select United States on the left sidebar. You should then be able to click “Apple to Try” on a huge variety of freebies!
As you can see from the items already listed, there are tens of thousands of people applying for these samples, so you're not guaranteed to get each item. But with so many freebies being offered, you're bound to get lucky in many of them! Plus you'll move to the top of the list if the brand is looking for your specific demographic. So mom's who buy stuff for their families are almost always offered freebies 🙂
As somebody who recently bought herb and vegetable seeds to grow in a window garden, I really hope I get a few of those Back to Roots freebies. Worst case, I end up killing my plants, but use the freebie on my hair roots!