I don't believe that this was accidentally stumbled across either.

The police said they believed that the man had stumbled accidentally.

He stumbled upon the property accidentally while driving around the lake.

The question is, did they accidentally stumble on a real phenomenon?

In doing so, he accidentally stumbled upon a unique recipe.

The results can be embarrassing, as if one had accidentally stumbled into a strange woman's bedroom.

The lines were so close that some soldiers accidentally stumbled into the camps of the opposing army.

"We just accidentally stumbled over a genuine question, and the shock is hard to recover from."

Accidentally stumbled across this and looked at some past podcast articles.