Soap berries (also called soap nuts) are a member of the Sapindaceae family. They are a very easy way to make plant soap for cleaning body and house. I use them for laundry by adding 5 or 6 berries to the load, then compost after maybe 5 loads. You can judge when they get spent of saponins.
I make hand soap by adding 5 of them to a bottle with a foamer top. Directions online usually say to simmer the soap berries for 30 minutes to extract the suds, but I blow off this step and pop them right in the foamer top bottle with water, giving them a good shake. It creates a pretty good foam and feels squeaky clean, but not drying at all. I’ve added essential oils to this but they ruin the suds and makes for a much less satisfying hand washing experience.
I also make shampoo and it makes my hair shiny and soft. I do the simmer step with 10 soap berries. When the infusion cools it’s ready to use. It’s thin, more like a cleansing rinse, but your hair will be so soft you’ll be petting yourself all day.