Gold Coin Purchase Question

This may seem like an odd question. Does anyone know if one is to buy gold coins from a local dealer, say in amounts below $10k, is there any sort of a paper trail created when using cash ? This is not to avoid any government audits or tax implications, but just more out of curiosity. It would seem over time, someone might be able to accumulate a fair amount of gold in small purchases and no one would necessarily know about it.