No, just keep the documentation in case of audit. You can't e-file an explanatory attachment except for certain situations, and if you filed on paper, the data entry clerk punching in your numbers would probably just lose the excess items.
Frankly, if your total non-cash donations are more than $5000 and you don't have an appraisal, you are at risk anyway, and submitting an explanation will just call attention to it. Wait and see if you are audited.
