Love hearing that you will be accepting cryptocurrencies for your CSA and farmers market! It's "the wave of the future". I posted a reply above talking about a tool that is out for mobile download called Steempay which might be something you could look into for a mobile on the spot exchange of steem. The developer is @kodaxx and is a steemit member.
Anyway, please update us how it goes! If I had some sort of good or service to sell, I would try to use steem for it. The more people selling who take crypto, the more people will buy with crypto, which will grow the real world crypto economy. { : thanks for the motivational post.