I Love You, Blue Kangaroo by Emma Chichester Clark is the adorable first story about Lily and Blue Kangaroo.
 
Every night Blue Kangaroo falls fast asleep, cuddled in Lily's arms. But as new toy animals start arriving, Blue Kangaroo worries that there just isn't enough room for him anymore. When he goes missing, Lily looks everywhere for him and it turns out NONE of the other toys mean as much to her as her first and favourite Blue Kangaroo.