Sardinia

"How do you locate them on the web?"

Google: agritourismo in sardinia.

There are a ton of them! Just google them and you'll get hundreds to chose from. Here's a link to a NY Times article about one I stayed at last September. Had a great time there. La Sorgente Agriturismo.
I also stayed at Cá la Somara in the northeast part of the island near Arzachena. Loved both of them and would recommend for a great stay. PM me if you want more info.

We found one on Trip Advisor, it was rated "the #1 in Sardinia;" It was in the middle of Sardinia, included dinner and good rooms, however it was a bear to find, so be very careful what you wish for. It was the only time we didn't stay in or near a city or town and it was rustic.
Since it was 3 years ago, my memory of the name is fuzzy, however, check Trip Advisor; I think there was about 13-14 of them in Sardinia.
"May the Force be with you!"

Plenty on Google, but great cookbook called The Southern Italian Farmer's Table - chefs who checked out agritourismo sites throughout Italy. A good resource and they have a section on Sardinia. Good luck and hope to hear more when you get back!