The only way to be a truly self-reliant gardener and to have security in producing your own food is to learn to save seeds. This is one area that does require some research and knowledge so that you are actually saving viable seeds. You will need some knowledge of plant cycles, pollination and isolation requirements. I guarantee if you garden long enough you will be become interested in saving your own seeds. Grandma and Grandpa were seed savers out of necessity. Seed saving today is a hobby and passion that some day may also become a necessity. The growing interest in preserving living heirlooms is essentially preserving our heritage and plant diversity. It's fascinating and fun and gives you a sense of security.
Planting an heirloom is planting history. Heirlooms are open pollinated plants (pollinated by wind or insects) with a rich history. They typically adapted to the region they were grown in with local disease and insect resistance and climate and soil adaptation. Their seeds were saved and preserved from generation to generation. Not every heirloom will grow well in your area. It requires some experimenting and time in order to find varieties that you can grow.
All open pollinated varieties will produce seed that is like their parents. Not all open-pollinated varieties are considered heirlooms but all heirlooms are open-pollinated. Seeds saved from hybrids will either be sterile or will be more like one of the parents is was breed from. There is a place for hybrids in the garden but not for seed saving.
I do recommend you have a resource on hand to be sure you understand what is required to save seed from each plant. Some plants are easier to save seed from than others. Start with the easy ones.
There is nothing more exciting than getting your own seeds out and planting and harvesting from them. Then saving seeds for the following year. As you do this with each generation the variety becomes better adapted to your soil and climate.
Below I have listed my two favorite references when saving seeds. Seed to Seed gives you some basics in seed biology, cleaning methods and storage. It then gives detailed information on plants in each vegetable family and includes some herbs.
The Complete Guide to Saving Seeds is a more detailed guide and includes techniques for seed saving vegetables, herbs, flowers, fruits, trees, and shrubs. If you enjoy the science behind seed saving you will enjoy this book.
These books only cover seed saving. There are other ways plants can be propagated. This is a whole new area of discovery and learning.