Gold should be 1oz or smaller coins from a sovereign mint like US eagles, Canadian maple leafs, SA Kruggerands, etc. Bigger stuff is more likely to be tungsten. If you need alot $$$ worth, get monster boxes of US gold eagles.

Silver is good in junk 90% US coins - quarters, dimes, and halfs from 1964 and earlier

1oz silver rounds from local pawn shops too