Uses:
Although used like a grain, since Chia is not a member of the grass family, like
Quinoa, it is not a true grain and is gluten free. Uses are too numerous to list here. There are whole websites and cookbooks dedicated to this subject.
The simplest, most practical and ancient form of consumption is to simply eat the seeds raw. The health and nutritional benefits are many and no preparation is required to receive these benefits. Like other seeds, for example sesame seeds, Chia can be lightly toasted which results in a richer, nutty flavor.
They can be sprouted and added to salads, ground and added to almost any recipe from energy / smoothie drinks, used as a thickening agent to replace corn starch, or used in place of bread crumbs in meatballs, meat loafs, or coating chicken. You can even use them to replace eggs in recipes by simply dry grinding Chia seeds into a powder and using one tablespoon along with three tablespoons of water for every egg your baked recipe calls for.
The bottom line is that Chia is as previously mentioned, a nutritionally dense food that is versatile and whose uses are really now just starting to be explored.
Harvesting:
The historical method for harvesting, which is also quite appropriate for small scale and home production,
was by bending the stalks over a container and beating the mature, dry seeds from the heads. Alternatively, the whole stalks can be cut, bundled and shocked to allow the drying process to continue and then the seeds are threshed from the heads. Hulling can be accomplished by wearing gloves and rubbing and then the final process of winnowing to clean the seeds for use can occur.
More Information:
FDA letter describing regulatory status of Salvia hispanica (chia).
USDA GRIN Taxonomy page.
Nutritional Data.