Serendipity

A happy accident

Pleasant surprise

Fortunate happenstance

Finding out things without being searching for them

Always making discoveries, by accidents and sagacity, of things which they were not in quest of

The occurrence and development of events by chance in a satisfactory or beneficial way, understanding the chance as any event that takes place in the absence of any obvious project (randomly or accidentally), which is not relevant to any present need, or in which the cause is unknown

See bridges where others saw holes