Through April 30th, Amazon is offering $10 Off $20 Whole Foods Market Purchase if you try Amazon Prime for FREE. All you need to do is sign up for a 30 day FREE Amazon Prime Trial and Amazon will email you the instructions on how to redeem your $10 credit. You can redeem your $10 through May 31st.
Note that promotional credit applies to any items available for purchase at your Whole Foods Market other than gift cards, alcohol, postage, and gift wrap services.