HELP! QUICK! Acccepted offer , now higher offer!

[Summer Segeleon]

I just accepted an offer VIA TEXT from a buyers agent. He was going to get the contract to me today (SO, not under contract, and didn't sign acceptance of offer or anything). New buyer calls and says they want the house and are ready to get into a bidding war if necessary. WHAT DO I DO? I know that ethically speaking I'm bound to the first offer but it wasn't that great and I would love to entertain this new one. Am I allowed to legally?