Unless you have more information, nothing.
The IRS requires that you have two types of documentation -- a receipt from the organization, and your own records of the items in enough detail that you can determine a fair market value. The receipt from the organization does not need to list a value, and it does not even need to be an itemized list, "34 bags of clothes and toys" would be acceptable. But separate from the receipt, you need a list of the items that were in those bags, with enough detail to determine a fair market value.
For ordinary items that can be a simple list. "14 pair dress slacks, 3 pair dress shoes", etc. You can then use Turbotax program values or your local thrift store values to determine the fair market value (whatever the store sells similar items for). For unusual or valuable items you may need more detail such as how you obtained the item, what you originally paid, and how you determined the value.
If you don't have a list of what items were in the bags, there is nothing stopping you from claiming a general value per bag. But if your return is audited, the IRS is likely to reduce or completely disallow the deduction for lack of proof. You have the burden of proving the value of your donations.
