How could June have picked up Beaver and taken him to the bank to cash the check? She had no car as Ward comes home from work and drives into the driveway. Did she pick him up at school and they walked? Did she borrow that sports car from the guy who bought it (the one that Beaver won?) Beaver says he’s never seen that much money when he gets the five dollars but uncle Billy gave him $10 and also there was $89 in that wallet.

And a few episodes before that she had to pick him up at school for a dentist appointment. I guess we're to assume Fred took Ward to the salt mines.