Maybe a pic would be helpful:
{{gwi:121959}}

I see nobody has responded, so I guess I will stick my neck out on this one. Maybe by now yours has colored up a bit and grown a tad. I have 20 various apples trees down in Dodge county about 30 miles south of you and none of my apples have the shape of yours. However, its shape and the lobes at the bottom suggest it might be a Red Delicious. Yes, they can be hardy in Minnesota and it was the leading commercial apple here before the winter of 1978 when most of them succumbed to the extra ordinary cold temps that winter. Then most commercial orchards yanked them out and replaced them with Haralson, Regent, or Fireside. Since then most orchards have gone with Honeycrisp or Zestar. ThereÂs another small orchard over in Dodge Center that has two 20 year old Red Delicious trees, they bear fairly well, and they are absolutely wonderful apples when eaten straight from the tree. It is only after they sit around in cold storage for 8 or 9 months do they taste supermarket disgusting. So see if they get bigger and turn red. If they are Red Delicious they should be ready to harvest around September 20th, although everything this year is two weeks late.

You might try taking a sample apple to the MN Arboretum for identification.

It looks like the wild apple tree in my yard too. Mine is small, maybe less than 10 feet tall. I hope it is Red Delicious. It's the kind I always buy because I do not know much about other varieties. One of the seeds from the mulch must have started years ago. Last year it had a few apples, but they were all gone one day. The squirrels probably ate them all. They were still green and about 1 to 1 1/2 inch in diameter. This year there are more apples and I put clear plastic water bottles around some of them. Hope that will help. They are green and about 1 1/2 inch now. I accidentally pulled some of them off and tried one. It was not bad, even though it was not ripe yet.