We had meat & cheese platters, buns & watermelon...and white cake with ice cream! Also, coffee, tea, powdered juice, water. We kept that simple.
I have been to one that had a potluck (food supplied by the family). Meat was barbecued. It was very nice. I heard of one recently that was just an outdoor picnic with a weiner roast...come as you are type of relaxed thing. I heard that it was unique with lots of fun. It rained, which added to the festivities.
Venue...a park would be nice. Have you ever been to Big Valley (Rosedale Park, Bernie MB)? It is absolutely gorgeous & can be private depending on who goes there for the day. It has a creek too, which might give interesting photo opportunities. I think it would be a great pick. If it rains, though, it could be difficult to get up & down the valley road. Another pretty place could be Victoria Park at the bandstand in Virden (contact the town if you want the bandstand), maybe Eternal Springs (park, fishing dams, swinging bridge). The Peace Gardens would be beautiful. I don't know how much venues might be to rent, but they have a lot of buildings there that they use for Legion camps, etc. How about area lakes down that way? There are many very beautiful ones to choose from.
I agree. Go explore. Check out options. Find something that suits your personalities and budget. Enjoy the pursuit of the perfect place.