Why would someone try to pay you for the gift you are giving them?

Lack of self worth (abused neighbor has done this); pride not to receive "charity"; genuine concern the gift's cost will cause economic harm to you; too many gifts given, so a sense of indebtedness develops - I have known folks who do this deliberately so they can leverage illicit "favors", etc etc.

Was it your mom?

Maybe, they don't want to reject the gift, but suspect the intention of the gift? I dunno.

I do that at times when we feel like we deserve it...maybe? It could be many reasons beyond me.

They clearly do Not like to receive gifts or burden the giver in any way possible.

... that's baffling. It's not how gifts work.

depends on the gift

call me superstitious but I wont accept a knife or scissors as a gift