Plant Guilds are found everywhere in nature and can be an invaluable addition to your gardening/permaculture experience. Guilds are a collection of two or more plants that are mutually beneficial to one another.
A couple of well known guilds are below but guilds are not set in stone. It is recommended that you experiment with your own guilds and find out what works best and share that valuable knowledge.
The Three Sisters (Or four)
Corn - Provides a trellis for the beans and Bee plant (Can be substituted with sunflowers)
Beans - Provides nitrogen to the corn
Squash - Provides shade and weed prevention at the ground level
Bee Plant - Provides attractive flowers for polinators
The Tomato Guild
These are probably the most common. Please share if you know of others or variations on existing guilds or have created/experimented with guilds of your own crafting. Also of interest are guilds involving fruit trees.