You can request an accounting from the executor, including financial statements and other documents evidencing the assets and claims against the estate (which he should be ready to provide), to evaluate the value and whether the assets have been (or will be) properly distributed. If there is a current court action and the uncle is already acting as executor, you can certainly conduct any discovery with respect to the estate if you feel there is any mismanagement.
Obviously, the facts and circumstances of each case would require a specific analysis in order to provide you with your specific options.
As my colleague points out, Executors in Texas are required to prepare an Inventory of the Estate. Under some new legislation, and depending on the language of the Will, this Inventory might or might not become a public record. But, as a beneficiary, you are entitled to know (1) what the Executor collected as assets of the estate, (2) what debts and expenses were paid with the estate property, and (3) what's left. Depending on the time that passes during the administration, you might even be entitled to a supplemental accounting prepared by the executor.
Executors in Texas are fiduciaries. They owe some of the highest legal obligations that the law can impose upon a person, and once appointed, your uncle will owe these legal obligations to you as a beneficiary. If you think that there is even a chance that your uncle will be less than transparent and forthcoming, you should consult with and retain an attorney early in the process. Stopping bad behavior in its tracks is much easier than putting the pieces back together after the fact. I'm sorry for your loss, and I wish you the best of luck.
This answer does not constitute legal advice. I am admitted to practice law in the State of Texas only, and make no attempt to opine on matters of law that are not relevant to Texas. This answer is based on general principles of law that may or may not relate to your specific situation, and is for promotional purposes only. You should never rely on this answer alone and nothing in these communications creates an attorney-client relationship.
As a fiduciary to your mother's estate, and an interested party, your uncle has to be very careful. A fiduciary obligation is about the highest that the law imposes in terms of candor and truthfulness. Any inappropriate accounting or misdeeds could subject your uncle to liability.
As your mother's son, you should have a pretty good idea what all assets are involved. As the executor, your uncle is required to marshal the assets and account for them. He is required to prepare an inventory and appraisement for the assets. Review the document to determine its accuracy and completeness.
Your uncle may have posted a fidelity bond. If your uncle has breached his fiduciary duties to the estate, you may consider making claim on the bond.