I certainly didn't grow up with a trust fund, but my parents were pretty well off. I can only reiterate what other people here have said, which is that you're the one who sets the tone. All you can do is show how how to be wealthy without being spoiled. I definitely wasn't aware or appreciative at the time, but looking back I can absolutely recall some specific things my parents did.
Money was never, ever treated flippantly. We lived in a really nice house, but it was a huge labor of love for them - they spent an enormous amount of time working with the architect and the builder to make their dream home. Looking back, I can't think of a single time where my family spent a lot of money on something they didn't really, really care about.
The only situations where money was no object were investments in the future for my brother and I. I wasn't even aware that that stuff was expensive growing up. We lived in an area with super shitty public schools for a while, so we went private for grade school. Holy shit is that stuff expensive! I had no idea until I was much older how much my parents must have spent for that. Which leads me into...
Don't insulate your kids. I mean, be a good parent and protect them from bad stuff, but don't let them live in a rich kid bubble. We moved when I was 11 or 12 and ended up in a district with good public schools, so I went there until college. Best thing that ever happened to me. It might have just been my particular district, but there was a lot of socioeconomic diversity there that I'd never been exposed to before. There were a lot of kids on public assistance, and a lot of kids with waaaaaay more money than we had.
Treat any amount of money like it has value, even if losing it wouldn't be a big deal. My parents bought me a car when I turned 16. They gave me a budget and asked me to do the research myself to choose a car. It wasn't a ton of money as far as cars go, but the fact that I had to choose it and think about the tradeoffs for myself (do I want a worse, newer car or a better older one? The internet says this one is the most fun to drive, but the other one has a cool stereo!) made me own the decision. I went to high school kids who had absolutely no sense of the value of their possessions - I remember one girl totaling her brand new Audi (she was fucking with her phone and ran into a tree) and she showed up three days later with a brand new Range Rover. I don't think she had any clue how much cars cost. As far as she was concerned, neat stuff just appeared and it was hers.
Having a sense of how much things cost - not just the number value, but the comparative value - is really important. The girl who wrecked her Audi had no idea that getting a new car was a big deal for most people. If I'd asked her whether she thought her new car cost more or less than a trip to Europe, or a year of college tuition, or a #7 combo with fries, I don't think she would have known. It's hard to value what you have when you don't have a reference point for what it's worth.
Don't just buy your son whatever he wants, even if he throws a fit, and even if all his friends have it. I got a job that paid something like $5.25/hour for a few hours after school every day in high school and I remember being super pumped because I could afford a new video game like, once a week if I wanted. I felt rich. I have no idea how my parents managed to make me feel like $40 a week was a lot of money when we lived in a million dollar house, but they did. I think it's because they didn't just give me shit growing up. Even what would be reasonably sized entertainment purchases as an adult were treated as kind of a big deal as a kid. If we got a Nintendo, it was disclaimered: "You guys don't usually get stuff this big, so it counts as both of your birthday presents this year," that kind of stuff. It seems like petty dumb rich kid stuff now, but I think it was valuable.