For 'conventions' there is an annual fair that we have. It focuses mostly on off-grid homesteading using draft animals, greenhouses, and sustainability.
Building your house, weaving your own fabric, livestock, herbal medicines, foraging food, low impact forestry, building the soil, ...
It runs for three days each fall, they routinely get 20,000 - 30,000 people each day of the fair.
I attend all three days. There are hourly workshops from 9am to 4pm, arranged in like ten different general topics. I start going over the schedule a month in advance, to work out my daily schedule of which ones to attend. I usually fill a notebook with notes from all of the workshops I attend. Local folks who have experience, and often who do these things for their business, sharing the tricks of how to survive and prosper.
www.mofga.org
http://www.mofga.org/TheFair/tabid/135/Default.aspx
My wife does a workshop in their outdoor kitchen, showing dried bean flour. She grows beans, and uses them to make breads, pizza crust, cookies, pie crusts, and snack crackers.