Question

what is the meaning of gather thistle gather pickle in English​

Answer 1

The actual phrase is;

Gather thistles, expect prickles

Gather thistles mean gathering things or information or anything in chunks, especially over a period of time.

Expect prickles means expect something very valuable or useful.

When one gathers something in chucks especially over a period of time, we actually have a good probability that the collection is of some big use or rich in quality.