Hi, I'm researching my husband's family tree and I've come to a halt as his grandfather was adopted. His name is Frank A Daly (A stands for Allie). He was born in CT and I believe his biological parents were from Rhode Island. He was adopted by Hannah Daly (Harney) born in Putnam CT and John Daly born in MA. Any hope of finding any info on the biological parents. How would I do this. Thank you.

At times they were just taken to the home, and were "adopted" by the family saying they were.
Perhaps they filed a paper at a court house or with a justice of the peace at the time. It is very possible there are no records at all.

One approach may be to search census records for both states, you may be able to pinpoint the time of "adoption" to a 10 year time frame.
Also search backward for census records from where both parents resided before marriage and after marriage before the child came to their home.
Is there an older family member that you can ask about the circumstances of the adoption or perhaps the child's last name before adoption?
Family bibles and church records if they were members of a church may also reveal some information. Perhaps a christening or baptism.
These "adoptions" may have been pretty common, I know of three in my family alone, two were children of family members, one a family friends child.
It may be a tough search without his birth surname.
I would start with the older family member and go from there.