Fungi could gain sentience, but not with humanity around. All animals from bugs to worms to people are decentants of a sea anemone looking critter that sat around in shallow murky water 600 million years ago. Anemones are kinda reminiscient of mushrooms.

Say a mushroom somewhere links its primitive light sensetivity to a automatic behavior, like quickly retracting if a shadow falls over it. BAM! The race is on. A major mass extinction then comes along and frees up some niches. These are going to be gimpy little creature with an extremely siplme nervous systems at first. Over tens of millions of years these critters will expand and diversify. Over the following hundreds of millions they'll refine their shapes and talents leading to complex behavior and ultimately to self-awareness.

interesting thing to contemplate.