Lavender for culinary as well as aromatic uses can be found online from a wide variety of sources. For the purest and highest quality lavender, you can buy directly from small family farms that specialize in producing lavender for culinary purposes as well as aromatic purposes. Small farmers often have more experience cooking with their own lavender, and can recommend the best varieties for savory and sweet recipes. They may even offer some recipes on their websites or with the lavender when you buy from them online.
If you really want to know how the lavender is grown, you can visit small lavender farms and purchase directly from the grower. Just knowing you can walk onto their land and see the plants may give you a sense of confidence about the pride a lavender farmer takes in producing high quality lavender.
Lavender is also sold online by large retailers, and you can even buy lavender buds from amazon.com. Be sure to research the source carefully if you are looking for culinary lavender. While most lavender is not harmful to eat, any lavender that has been treated or amended with synthetic lavender scents is probably best avoided for culinary purposes. And if you get the wrong kind of lavender your dishes will not taste as good, either.
For leads to lavender farms within the US, check out the websites for the Sequim Lavender Festival (www.lavenderfestival.com) in Sequim, Washington, or the Oregon Lavender Festival (http://www.oregonlavenderdestinations.com/festival.php). Eastern Oregon and eastern Washington State have the ideal climate for growing lavender. There are a large number of small farms in the region, all growing high quality lavender, both for culinary and aromatic uses.