How can I mitigate my husband's hoarding tendancies?

We had a garage at our old house that, over time, got filled to the rafters with things he “Might need some day” especially mechanics parts. And after the garage was packed he just started stashing stuff on the around the house.
I would secretly filch things and send them to Goodwill or trash them.
We don’t have garage now
What we do have is a utility room. This house was a rental when we bought it. In the utility room I found about 30 outlet covers, probably by the landlord.
I went to throw them in the Goodwill basket and he stopped me. No idea why.
The house was built in 1950. When Rick was doing the tear out he came across about 1000 square nails. He saved them all in an empty pop box, convinced they were antiques and he could make money off them. I researched. He can’t. They aren’t the antiques!
There is a big, huge sink in the second bedroom. I was trying to get rid of it. He said no, he was going to sell it. And there it sits. He hasn’t cleaned it up or taken a picture to put it on the Market place.
We bought some beautiful cabinets and counters from an individual. We had to take it ALL! As a result we have a very nice kitchen island in our living room.
I asked Rick if we could get it cleared off and put the granite counter top on and get it ready to sell. I was sitting next to him and I could feel him tense up.
What is this? I’m so frustrated.

Trying to talk to him just leads to arguments.