You can bridge Your USDC & MATIC from Ethereum Mainnet to Polygon Network and back using any of these suggested options:
A low fee bridge that easily allows you to bridge your assets between Ethereum & Polygon quickly. Unofficial bridge so use at your own risk.
Bridge funds using the Official Polygon Bridge
The official Polygon bridge. Most reliable but can be expensive when Ethereum gas fees are high.
Bridge funds using Umbria Narni Bridge
*For low to mid size transactions
New and popular bridge that allows you to send assets between Ethereum and Polygon for much cheaper than the Official Polygon bridge and quickly, but is unofficial so use at your own risk.