Round Balls, Round Balls (Round) Fairly goofy big: try just pitching the creatues up in the air, the ball, the bunny, the bear, the kitty, and the elephant. That should amuse the babies!
Where's My Teddy by Jez Alborough. An all time favorite. Don't forget to bring the bears, and then sing "This is Little".
Not a Box by Antoinette Portis. Babies might not get the gist of this exercise in imagination, but they will certainly get the concept of having a good time with a box.
By all means collect all the noisemaking baby toys and pass them out for a grand finale:
Rattle up high, rattle down low,
rattle fast, and rattle slow.
Rattle all around -- don't stop! -- don't quit!
Rattle till you're tired and ready to quit.
Have them count while you throw the beanbags into the box. Get the parents to join in.