Yummy Mummy. Elin celebrated her 33rd birthday in The Bahamas with her two kids....

The sometimes-reliable "National Enquirer" says TIGER WOODS is trying to get his ex-wife ELIN NORDEGREN back.  And he's so desperate to re-win her heart that he's offering her a $200 MILLION prenup.

Sources say Elin is potentially interested, but she's upping the stakes.  She wants a $350 million no-cheating clause.

It's not clear if that means $350 million on top of the $200 million . . . or $350 million total.  Either way, it's a big chunk of Tiger's fortune, which is still estimated at $600 million, even after he gave Elin a $110 million settlement when they divorced.

But a source says Tiger isn't worried about the money . . . quote, "He has never recovered from being dumped by Elin.  He's dated a lot of models and bimbos but none of them were more than a one-night stand."

The source also claims that Tiger and Elin recently started having interracial sex again.