If you can get to Grindelwald on a Saturday morning, this stall run by local women farmers selling their own produce might interest you:
http://www.myswitzerland.com/ en-au/events/event-35504981.html
Their own website is only in German, but Google Translate does a reasonable job of translating the gist of it.
http://www.maertfrauen-grindelwald.ch/
This page describes the types of products they sell:
http://www.maertfrauen-grindelwald.ch/produkt e-angebote/
Information about the women themselves is here:
http://www.maertfrauen-grindelwald.ch/über-uns/
For milk and cheese products from the region, there is also this store in Wengen, called Chäs-Gruebi:
http://www.chaes-gruebi.ch/spezielles/U nser%20Laden/laden.htm
On the Switzerland Tourism Events page, you can filter by location, date and category “Gastronomy” for other possibilities.
http://www.myswitzerland.com/ en-au/events.html
There is also the Swiss Tavolata, where women farmers offer fine dining on their own farms, though none are in the two locations you mentioned:
http://www.swisstavolata.ch/i ndex.php?language=en
Not all farms are accessible by public transport, but many are, and information about transport is included in the information provided about each offer:
http://www.swisstavolata.ch/t avolata/
Alpenrose