Pregnant actress Drew Barrymore doing a photo shoot at the Huntington Library in San Marino, California on April 30, 2012. Credit: FameFlynet

Drew's a happy mama-to-be in springtime!

On Monday, a pregnant Drew Barrymore hit the gardens of the Huntington Library in San Marino, Calif. for a photo shoot.

Although still mum on her pregnancy, the Big Miracle star, 37, embraced her newfound curves in a breezy, pink, long-sleeve dress -- complete with a black belt at the waist that accentuated her expanding bump. In another shot, the actress (who will wed the baby's dad, art consultant Will Kopelman, next month) absolutely beamed as she held a parasol for the quaint shoot.

"She is so thrilled to be expecting," a source told the latest Us Weekly of Barrymore. As she prepares for impending motherhood, the star is also just as hard at work planning her June walk down the aisle.

According to a source, the mom-to-be will don Chanel for her ceremony, to be held at her Montecito, Calif., home. (Her future father-in-law, Arie Kopelman, is the former CEO of the fashion house.)

Barrymore -- who began dating her man in January 2011 and accepted Kopelman's proposal a year later -- is in full-tilt wedding planning mode.

The twice-divorced actress "is really focused on the wedding right now," says the friend. "She will be even more excited about the baby after that!"