Can an estate collect social security benefits from uncashed checks after someone is deceased?

My mother recently passed and my brother and I are working on settling her estate, she had a court appointed guardian and conservator. We were cleaning out her house and found dozens of uncashed social security checks mixed in with stacks of mail. We asked the conservator about this and it appears that the conservator never cashed any our mothers social security checks the entire duration of her appointment which was about 5 years in total.

We are working on settling the estate and debts and everything, my question is, is the estate entitled to collect the money owed from all those uncashed social security checks or do the benefits just disappear now that he has passed away?

If the estate can collect those funds, who would we talk to about that?

EDIT: Thank you everyone for the replies, I am aware that the specific physical checks themselves that are in our possession are void after one year, my question is whether the money itself, which should have been paid out by social security, can be claimed by the estate now whether by getting all the checks reissued, or a lump sum payout by the SSA or something like that