This is speedwell. I’m not very familiar with the genus and might be mistaken, but I believe it’s slender speedwell, Veronica filiformis, a non-native Ontario wildflower (based on threadlike flower stalks and roundish leaves).
Speedwell was one of the rabbits in one of my favourite novels as a boy, Watership Down. He was energetic and good-humoured. I got to know Hazel, Speedwell and the other rabbits around age 10 when I was also forming a life-long affection for flora. For 45 years I’ve had a soft spot for speedwell and wanted some in my garden.
This slender speedwell was growing in our lawn, which gets mown regularly, not by us. I like this seed-bead-sized perfectly blue flower so much I’ve transplanted a couple roots into my small garden where it can sprint and tell jokes around the larger plants.