I’m a big fan of surprise balls. Not that I’ve had so much experience with them, but I found these ones at a store in SF called Unionmade, and they’re great. The woman who makes them seeks out dead stock vintage toys, and each surprise is a treat. They’re not cheap at $55 a pop, but they are more fun than an Easter basket. They also keep them busy for about 20 minutes while they unravel them.
Unfortunately the Unionmade surprise balls are sold out right now, but I looked on Etsy and found several options. They’re a fraction of the price, but not as big, and definitely not 15 toys (but do you really need that many anyway?!) You can also learn how to make your own. I thought this site did a nice job of how-to, along with clever ideas of what to fill it with.