Of course, I grew up eating this casserole (one more thing Mom could make out of hamburger since we had a plethora of living on a farm). When I went to college, my roommate Clarice introduced me to the "variation" of adding green peas...which I really enjoy! I've also added grated cheese a few times just to entice the kids a little more and "mask" the green veggies.
¾ lb hamburger
1 can cream of mushroom
½ bag of tater tots
½ bag of frozen peas (I'm sure you could easily substitute most frozen veggies here...but I haven't been that adventurous yet :)
Brown hamburger, add cream of mushroom, peas, and half of tater tots. Mix until the mixture is warm. Put into a pan and spread the rest of the tater tots on top. Put in oven at 350 for 25-30 minutes. Cover with foil until almost done and then uncover to crispy tater tots.
ETA 9/5/2016: I made this for a freezer meal swap. The only change would be to cook it at 350 for 1 hour since it would be frozen at the start.