Trent Richardson -- the #3 overall pick in the 2012 NFL Draft -- turned 21 years old last night ... and to celebrate, dude hit up a trendy Hollywood restaurant with an Oscar Winner. Not bad ...
The Cleveland Browns running back had his birthday dinner at Mercato di Vetro ... alongside Jamie Foxx.
It's unclear how the two know each other ... but they're probably both in town for the ESPYS tonight.
We're guessing Foxx paid for dinner ... since Richardson has yet to sign his NFL contract.