Minnie Driver and about 40 guests gathered Saturday at a friend's home in Malibu for a baby shower.
The house was decorated with pink and white peonies, and it was a casual affair, with guests sipping basil lemonade and eating finger sandwiches and berry cake from Sweet Lady Jane.
"Minnie loves the cake," says a pal.
Driver opened Gymboree Brand New gifts, while guests hand-painted onesies for the baby and signed personal notes in a book to be given to the mom-to-be.
"It was a beautiful day," a guest tells PEOPLE.
The British-born Driver, 38, has decided not to find out the sex of the baby. She has said little about the father
, except that's he's English, "sort of in the same business," and that they have no plans to marry.