My condolences to you and your family!
It is difficult when a close relative dies, even when you haven't seen or interacted with them for many years. In some ways, it is harder as there were so many missed opportunities that can never be realized now.
Things will get better over time especially if you reflect on good memories and push the negatives away.
Although her possessions and money may not be something you wish to deal with right now, it is an important aspect of your mother's life that needs to be settled sooner than later.
I don't know about your state but here, if a person dies 'intestate' (without a Will) the rules of succession are Spouse - Children - Parents - Siblings - Neices/Nephews.
As you are your mother's only surviving child, you have priority to receive your mother's estate over your uncle. If your father remains living and they were not legally separated or divorced, he would have priority over you. If no Will is in-place, there would be a need for a court proceeding to assign an Executor to handle the settlement of the estate including submitting her income tax and determining a value of the entire estate for tax purposes.
If she did have a Will in place, the Will would first need to be Probated (legally recognized and notorized as "THE" official Will). This would be handled by the Executor that she should have named within her Will. The Executor is the only person that legally can deal with the estate and can gain access to bank accounts, sell property, submit insurance claims and the like.
If your mother had any life insurance policies, she would have named someone as a recipient and each policy would payout to the person named regardless of the terms of the Will.
Until these matters are addressed, property and assets should not be touched or given away as there is no clearly identified beneficiary(s). As your Uncle has already interferred with matters, he may be legally liable for the value of the items if it turns out that he was not entitled to act as Executor or was not to receive the items, even if he gave them away and didn't profit from them.
As you are an interested party and likely your mother's legal next-of-kin, you have legal right to know and pursue all the particulars of her estate regardless if you are or are not to receive a portion.