1) Preheat to 350°F.
2) In a saute pan brown the hamburger and add to large bowl.
3) Brown bacon in the same saute pan and add to the bowl. Make sure to add just the bacon, not all the fat!
4) Drain the butter beans and the kidney beans. Add them to the large bowl, along with the baked beans. Mix well.
5) Add the onion, brown sugar, catsup, dry mustard, vinegar and salt to the bowl and mix well.
6) Spoon mixture into large casserole dish (2-1/2 qt.) and bake, uncovered, in 350 degree oven for 1 hour.
7)This side dish is great with any BBQ and make sure to enjoy this side dish served warm!