The word 'strike' means to hit or dash on or against something, but I guess that word has another meaning in the context below. It seems to mean 'find' but I am not sure. What does it mean below exactly?
When a blue-jay lit on that house, with an acorn in his mouth, and says, 'Hello, I reckon I've struck something.' When he spoke, the acorn dropped out of his mouth and rolled down the roof, of course, but he didn't care; his mind was all on the thing he had struck.
—from 'Baker's blue-jay yarn' by Mark Twain