Raising a vegetable garden is a really enjoyable and engrossing hobby. It's wonderful to take a plot of ground, plant some seeds in it, care for that ground by removing weeds and adding nutrients, and seeing the plants grow and produce fruits and vegetables. Not only that, if you're using heirloom varieties, you can save the seeds and plant them again next season.
So, how does this make money? For one, you can take the food and eat it yourself, eliminating the cost of meals or meal ingredients and keeping that money in your pocket. You can also take the extras and sell them. Post what you have for sale on Facebook or take them to a farmers market. Put them on a table in front of your house with a jar and a take what you need, pay what you can card. Look into selling the extras to local grocers. You get the idea.
Obviously, the bigger the garden, the more food you produce, and the more food you produce, the greater the proceeds. It's all about how much you enjoy the hobby and how much time and energy you're willing to invest.