There are lots of easy to grow vegetables for Calgary zone 3. Someday when I am done the major projects in the rest of the yard, and when those raised beds are done, I will grow more vegetables myself, but for now I choose the easy route. I only start tomatoes inside because they need a head start, and the rest of my veggies are ones that are easy to grow by sowing them directly in the ground when it's warm enough. I also only grow veggies that are really worth the space, which is at a premium in my shady yard: carrots, peas, beans, lettuce, spinach all taste infinitely better picked fresh that those tasteless facsimiles at the grocery store. I also grew pumpkins last year but decided they take up too much space.
Here is a schedule for planting these as well as many other vegetables with times for seeding indoors, transplanting outside, and seeding directly outside. I copied it with some modifications from The Calgary Gardener, a must-have book by the Calgary Horticultural Society.
Recommended reading: Garden Rant Rules for Beginning Vegetable Gardeners