Commonly considered a weed, young dandelions provide excellent salad leaves (though larger, older leaves become bitter). They grow wild all over Europe, the US and Asia. If you pick your own, do so in the spring when the leaves are small and sweet and before the flower has formed. Take care though, as they may have been chemically sprayed and, if so, should be avoided. Also avoid picking dandelions by the roadside as they will have absorbed petrol fumes.
More dandelion recipes
In some parts of Europe, cultivated varieties of dandelion are available that have longer, more tender leaves. These are available from specialist herb growers in the UK.