Recycling is all the rage, so why not do it with your food?
You can actually regrow some of your food and do it inside and become pretty impressive to your kids! Just make sure you use veggies that are slightly fresh and remember to pay attention to your future plant, making sure it has the water and light it needs.
If your romaine head of lettuce is getting weak just get rid of the leaves and keep the stalk. This is pretty amazing. If the bottom of the stump is saved and placed in water, regeneration and new growth will occur. Place each piece in a half-inch of water, check the water level daily, and marvel as the stump starts to sprout and grow. No dirt needed just a cool environment and a lot of sun.
Nobody likes the end of a carrot except maybe a horse but they are pretty good for creating carrot tops. You won’t be able to grow carrots from the tops but they are good in salads or cooked. More people tend to use them cooked, especially in soups, than raw. Get carrots that have a little bit of green on the top. Cut off the top 2 inches from the crown of one or more carrots.
Place the in a shallow saucer cut side down. Add water so that half of the top is submerged in water.
Place it near light and add water daily. In a couple weeks you will have green tops.
Celery is similar to the romaine lettuce, cut off the bottom of the stalk and place the chunk in a bowl of water and in a few days marvel as little stalks start to form. After 5 days you should transfer it to a planter with dirt. Cover it completely with a mixture of dirt and potting soil. Three to four weeks and you have a nice celery plant with little stalks. Never need to buy celery at the store again.
As long as you aren't kissing anyone onions are great and easy to grow. Start off with the bottom of an onion and chop it off at the roots. The more roots the better. Allow to dry for a few hours to a couple days in a shaded, well-ventilated area to allow for callousing. Get a little starter flower pot and fill it 2/3 with soil. Make sure you make it very compacted. Create an indentation in the center to cradle the onion bottom and allow for good soil contact. Cover with 1-2" of soil. Water as needed.
How about growing an avocado tree from its pit? This one is a long-term project. It actually takes a little longer than watching water boil. Really long term -- 10-13 years -- but heck, it's worth a shot.
Wash the seed. Using three toothpicks, suspend it broad end down over a water-filled glass to cover about an inch of the seed. Put it in a warm place. You don't want direct sun on it. Add water as it's needed. You will probably see roots and stems in about 2-6 weeks. When it is 6-7 inches long cut it back to three inches.
When the roots are thick and the stem has leafed out again, plant it in a rich humus soil in a 10-1/2" diameter pot, leaving the seed half exposed. Light water with a deep soak once in a while. Lots of sun at this point. Once it is 12 inches high cut it back to 6. A plant grown from seed will take anywhere from 5 to 13 years to flower and bear fruit.
The moral of this story is don't throw it out, grow it out!