My mother gave me a collection of her poems. She is now deceased. She always wanted to be published. She never copyrighted her work. Her surviving spouse and my brother have no issue with me doing this. Do I have to worry about any legal considerations?
First, my condolences--I hope you and your family find peace.
As for publishing her work, everything I've read emphasizes next of kin (the person who can legally act in their stead) when publishing the work of a deceased person. The person's manuscript (or computer that contains the text file, etc.) is considered personal property, and passes to the next of kin to deal with as they see fit. As long as you have the spouse's (your mother's next of kin) consent, I see no problem with you publishing the poems.
If you're still unsure or run into problems, I'd get in touch with a probate lawyer.