Original: Andy's mom accidentally throws the other toys away, thinking that they are no longer wanted; they escape and decide to climb in a box to be donated to the Sunnyside Daycare.
Simplified: A misunderstanding with Andy's slightly aged mother (Laurie Metcalf) results in the other toys being thrown away, making them think they are no longer wanted; they escape and decide to climb in a box to be donated to a daycare center called Sunnyside, along with Woody.