Answer:
Lennie was given a rubber mouse because he wouldn't be able to kill it, he didn't like it because it wouldn't be any good to pet.
Step-by-step explanation:
"The hell with the rabbits. An’ you ain’t to be trusted with no live
mice; Your Aunt Clara give you a rubber mouse and you wouldn’t
have nothing to do with it."
"It wasn’t no good to pet," said Lennie.