First there is the actual produce. Not only is it incredibly good for you, but fruits and veggies make beautiful seasonal displays and offerings. Also at our market there are many people who sell herbs and flowers, both fresh and dried, and I could get much of the ingredients I needed for a spell pouch, dream pillow, or for some homemade incense or smudge.
There are also two fantastic soap vendors at our market - both of whom use organic ingredients and locally grown herbs and flowers in their soaps. If you are looking for something special for a ritual bath - organic handmade soap is it!
I've also purchased sarongs and silk fabric and a gorgeous wrap skirt at an artisan's booth. I've used a sarong and the fabric for altar cloths, and the wrap skirt is one of the special pieces of clothing I set aside for magical work.
Something you can find at most farmers markets is local honey. I am in LOVE with local honey! Firstly, it's a fabulous way to stave off allergies. I started getting some sniffles this Spring and after a teaspoon of honey a day, I am allergy free! The idea is that the bees collect pollen from the local plants (many of which are responsible for your allergies) and by dosing with the honey, you are in essence allowing your body to build an immunity to the pollen from those plants.
Also, honey can be used as an offering (Faeries are said to love their milk & honey) or used for 'sweetening' someone (more common in hoodoo and rootwork.)
So, next time you visit your local farmers market, remember that all those wonderful wares can be used for more than just making a Summer meal - they can be used for making a little magic too!