If you just dropped the toys off in a bin at Walmart you can claim the donation and use the Walmart receipts as a basis for the amount. It is possible to deduct these donations on your taxes as long as you plan to itemize.
If your donation is less than $250, you can claim a deduction for clothes (or toys) left in a drop-off bin without a receipt from the charity. Typically, you need a receipt, but the IRS specifically lists an unattended drop-site donation as an instance for which getting a receipt is impractical. You do, however, need to keep a record of what you donated, when and where you donated it and the charity to which you donated it in case your deduction is questioned.
Yes you can.
If you donate items to an unmanned drop box, you can still claim the deduction. However, you need to have the name and address of the charity, the drop box location, a detailed list of the items donated and the value.
You cannot - the Walmart receipt only shows you bought toys. You need a receipt from the charity.