pay dirt

pay dirt  {n.},  {slang}

1. Золотоносная грязь (песок) с большим количеством золота.

2.  {informal} Ценное открытие, находка. — Часто исп. в сочетании: "strike pay dirt".

When Bill joined the team, the coach struck pay dirt.

Jean looked in many books for facts about her hometown, and finally she struck pay dirt.

Ср.: STRIKE IT RICH.