Lavender is one of the best known of essential oils and it is the perfect addition to your home's first aid kit. Lavandula officinalis has dozens of uses around the home.
The most useful one that I have found is that it will relieve burns. Dab the burnt area with a little neat lavender oil and allow to dry. This really works well for minor burns.
Lavender is an antibiotic, antiviral and antiseptic, so it is excellent for use in mild acne, blisters, cuts, insect bites and stings. Use on itchy skin, dry skin, and even sunburn.
It also eases bruising , dry cough (rub onto chest or put on a handkerchief), and lifts PMT (throw a handful of the flowers into your bath).
Lavender is safe to use directly from the bottle and there is no need to dilute it. Make sure that you buy 100% essential oil because the cheaper, "fragrance oils" are not the same. They tend to contain a whole range of other substances, from turpentine to creosote, and you don't want that on your skin.
Although lavender is a safe essential oil for all the family to use, never take it internally. There are recipes on the Internet for mouthwashes using lavender oil but I would never advocate this. (I am a fully qualified aromatherapist here in the UK.)
You can, however, eat lavender flowers. It does sound highly unlikely that that you might even want to try, but ground lavender flowers give an interesting flavor to custards, salads and biscuits.