Is it permitted to take/use an item that belongs to your close friend/ family member without asking permission if you know without a doubt that they would let you have the item if they were asked?
Example: My good friend has some snacks/tissues lying on the table. Can I take the item if I know he would allow me to have it?
I am not referring to a case where it is a mitzvah.
As a general rule it is stealing even if we take something from someone that is has very little value, however on certain items usually we can safely assume that the person is not going to mind, such as a toothpick, a tissue, a cup of tea. This is because people in general are not particular about this and wouldn’t mind, even if the item is worth more than a perutah. Nevertheless it is a pious thing to ask the owner permission specifically
Regarding taking items or using them, and these are a type of item that a person would not allow just anyone to take from it, but you know that if you would ask him he would surely say yes, this is controversial. Therefore a person should preferably not take such things from a friend etc. without his permission, however if there is a strong need he can be lenient, and rely on the permitting opinion. However if the person was asks a few times in the past and he allowed it, then I is permitted according to everyone.
If it is a mitzvah item, such as a tallis then it may be used, however care must be taken that using it will not inconvenience the owner in any way, i.e. he might want to you use it now. It also must be put back exactly the way it was taken, and it may not be removed far from where it was taken as the owner may look for it.
CH”M 351-1, Aruch Hasulchan 351-1, Pischei Choshen Vol. 1 chap. 1 ftnt. 38, M”B 14-13, Shulchan Aruch Horav 14-10.