You can also summon scratch and he will find it for you. Apparently he even finds chests that don't have a visible survival check. But I can't confirm that because I never have him summoned.
Yup, it's an ability called "Find Familiar: Scratch" You need to have had a few interactions with him in the camp before the ability appears. I think it can be found in the "Common" section of your spellbook once you have it.
You also don't need to worry about him dying. You can always resummon him. But he is fairly useless in combat and other familiars are better.
Scratch is a good boy. He brings me gifts in camp. Last night he gave me a potion of speak with Animals...wonder if he is telling me he has something he wants to tell me...
You can also summon the owlbear cub, Mayrina's husband Connor, Us the brain creature from the nautiloid, 4 ghouls from the Necronomicon of Thay, a fairy from the broken moonlantern, the quasit Shovel. I think that's all of them.
There is a bug where he gets stuck either in blighted village or in your camp behind target dummies near blighted village. Then the summon spell is greyed out. To fix it I had to go back to blighted village and then I could cast the spell.