Stablecoins are an essential part of a crypto investor's portfolio. HODLing and Diamond hands are part of the game, but every now and then profits have to be taken out. Or if you have a lower risk appetite, you could keep a higher share of portfolio in them.
Why would anyone has to leave them idle when you can earn excellent yields on them. Here's some of the options on Binance smart chain, ERC-20 and Matic Network.

BSC

The leader, Pancakeswap Finance have high yield farming yields on TUSD-BUSD pair and UST-BUSD pair at 15%.

Cafeswap Finance offers a 12% APR 

Pancake Bunny has a respectable 15% yield on BUSD-USDT pair.

Wault Finance has a high 20% yield on DAI-BUSD

Apeswap has 18% on the BUSD-DAI Pair

Alpaca Finance offers 18% on USDT

ERC-20

The gas fees are the highest in the Ethereum network.
If you are looking to put your money to work, Nexo is a major player. You could earn around 12% by depositing there.

You could earn on Truefi, the uncollateralized lending platform which provides 30%.

Vesper Finance has a yield close to 16% for USDC.

Matic Network

Quickswap on the Matic Network has a APR around 16% on stablecoins.

Happy farming, everyone.