Self Pollination

Mother Earth News, Sep/Oct 1987
Bring new pleasures and superior plants to your garden
By Nancy Bubel

Some common self-pollinators are tomatoes, lettuce, peas, snap beans, soybeans, lima beans, endive and escarole. Barley, wheat, oats and cowpeas also self pollinate. Peppers do, too, but they will cross when in sects bring in pollen from other kinds of peppers. (If you want to get technical, all self-pollinators can cross with other varieties of the same vegetable in from 0.1% to as much as 5% of the plant populations, but for ordinary back-yard seed saving you don't need to isolate them. I've saved tomato and lettuce seeds for 15 years, and the plants have always come true.)

Mother Earth News, Sep/Oct 78
Cross Pollination

The easiest way for the beginning seed grower to avoid [cross pollination problems] is to concentrate on self-pollinating vegetables - such as lettuce, okra, beans, peas, and tomatoes - which have flowers designed in ways that discourage or prohibit fertilization by other plants. (Peas, for example, have already pollinated themselves by the time the flowers open!) Still, to restrict your efforts to these plants is to miss out on much of the fun, challenge and satisfaction of growing your own seeds.