After using the
bitcoind -regtest generate 1 command, where does the mining reward go? I tried list accounts and check balance for account "", but the balance always showed 0.000000.
To you, but with a delay.
What you're observing is the maturity period: the coins generated by a block can only be moved after there are another 100 blocks on top.
If you generate another 100, your balance will start increasing.