Thank you all for your replies.
With further consideration, I believe charities would not want a donation that may have more financial liability (expenses) than possible gains.
I have discovered filing the appropriate documents with each county will probably exceed the value of the interests as well.
Anyone have any idea what running/verifying title might approximately cost? Is this done by a landman or a lawyer? I have already consulted a lawyer about selling the interests, and he said the cost of his time would far exceed the value of the interests.
Any ideas of what to do? Thanks!