Serendipity is considered “a happy accident”, the lucky tendency of finding interesting or valuable things by accident.

Serendipitous is the adjective.

Chili peppers were a serendipitous discovery in the New World.

(Chili peppers were a lucky discovery in the New World.)

Amtrak’s serendipitous discovery of a braking flaw could lead to fundamental reform.

(Amtrak’s lucky discovery of a braking flaw could lead to fundamental reform.)

–adjective 1. come upon or found by accident; fortuitous: serendipitous scientific discoveries.

2. of, pertaining to, or suggesting serendipity.

3. good; beneficial; favorable: serendipitous weather for our vacation.