Cornsnakes are the best but for a young child you should try and get one thats atleast a year old, hatchlings can be a little nippy and flightly. Like snakeguy said, you never should feed live mice, some that are old enough can scratch and bite your snake and some snakes aren't very good killers and swallow the mice alive. And just so you know crickets aren't as good are a nice mouse for your snake.
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People Who Say Money Can't Buy You Happiness Obviously Didn't Know Where To Buy A Herp

2.0 Corns (CC & Norm: Peppermint & Guttata)
1.0 Ball Python (Norm: Ade)
0.1 Cali Kingsnake (Norm: Lady Macbeth)
1.0 Bearded Dragon (Yellow x Gold: Vito)
0.0.1 Leopard Gecko (Norm: Pardus)
0.0.1 Marbled Gecko (Norm: B.B.)