Here is another recipe from B.J’s aunt  Janet:

Crockpot Rump Roast
3 or 4 lb. rump roast
1 10.75 can cream of mushroom soup
1 10.75  can condensed beef broth
1 pkg. dry onion soup mix
1/2 medium onion, sliced
1 garlic clove, sliced
black pepper to taste

In crockpot, add road after you spread the dry onion soup over it.
Add sliced onion to top of roast and in crockpot.
Add garlic and black pepper.
Then add the cram of mushroom soup and condensed beef broth.
Turn the crockpot to high temperature for one hour.
Then turn temperature down to low and cook 6 hours.
If using a larger size roast, just add 2 cans of mushroom soup and 2 cans of condensed broth and cook an extra hours.