I assume you receive cash & bank it every now & again (unless your mattress is particularly lumpy?!)
Set up a new Bank Account in QB - Petty Cash or Cash at Hand.
Use this account to receive payments in QB & also to record the small purchases you make.
When you pay money into your bank, simply record this as a Transfer between Bank Accounts in QB.
If you happen to buy any personal items with the cash, this can be recorded as Drawings in the usual way.
I'm sure there will be a way to pay cash from Undeposited Funds account too - but I prefer to record Petty Cash as a separate account as above.