I'm an adult male in his late 20's and have been living on my own for several years with a good job. My dad every so often will go to garage sales or the store and see something interesting he thinks I'd like. These are usually small things, typically under $50. However, I have my own tastes in things and what would fit in my life. As an example, he may know that my coffee pot broke and I'm looking around for a new one. He'll buy me a red one when my kitchen is color-coded stainless steel/black.
I just found out he bought me a shelf, which I need, but haven't bought on my own because I was still trying to figure out what style/shape would best fit in my apartment. If I see something he gets me and I don't like it, I start feeling ungrateful. What makes it even worse is that I'm much more well off than my dad.
How can I convey to him kindly that I just don't like some things he buys me and that he should either stop buying me things or consider that I won't like everything he gets?