I love having plants growing all over my house and it's even better when they're free! Here's a a few I have currently growing.
When your potatoes sprout just plant them about 2 inches deep in potting soil. They make a nice sturdy green houseplant.
I found a seed pod dangling from a vine while out for a walk and decided to plant the seeds. I now have this pretty plant growing and it can be pruned back so the vines don't take over.
I found the little fruit from this tree growing out by the swimming pool at the apartment complex I live at. Any fruit with seeds are fair game for my indoor garden.
For succulents like jade just cut a little piece off, even a leaf will sometimes work. Stick the branch or leaf in soil and with luck you'll have a new plant!
I raided my spice cabinet and planted a few of every whole seed I had! Here we have mustard, fennel, cumin and coriander.
My avocado tree is nearly three feet tall! I started it by sticking toothpicks in an avocado pit and suspending it (fat side down) in a glass of water. When it was big enough I planted it in potting soil.