Few years ago I have applied for a US visa. I wanted to go there for a weekend with friends or for vacation. It didn't work out, some years have passed and recently I have convicted a felony (nothing special, nothing criminal, but it stays in my "papers"). I'm in a position where I could go there for a weekend, but I am too afraid of going to be put on the plane back during visa check or whatever. Is there any way I could verify if I can still get there for a weekend trip?
You have a valid US visa, but you are concerned that you may have become inadmissible since the visa was issued. You would like to have a better sense of whether you will be allowed into the US.
As other answers have noted, there is no way to guarantee that you will be admitted. An immigration officer at the border can always deny admission. But there are some things you can do to reduce the probability of being denied admission at the border.
1. Learn the rules
Evaluate yourself against the statutory grounds of inadmissibility, which are set forth at 8 USC 1182. You are concerned about criminal grounds of inadmissibility, so you should look at section (a)(2). There you will find that grounds of inadmissibility include "crimes involving moral turpitude" (CIMTs). An internet search indicates that CIMTs include fraud, and a "tax related" conviction such as yours certainly could have involved fraud. Nonetheless, there is an exception if there is only one conviction and the maximum sentence you faced was one year imprisonment or less and your actual sentence was six months imprisonment or less. If your conviction does trigger this section, you can apply for a waiver under sections (a)(2)(F) and (h).
2. Consider using preclearance
Travel to the US through an airport with preclearance facilities. This reduces the severity of the consequences of a denial of admission.
3. Apply for a new visa
Apply for a new visa, revealing the details of your conviction. Your admissibility will be evaluated by the visa officer. While the immigration officer will still make a second determination of admissibility at the border, the determination is unlikely to be different from the visa officer's.
None of these suggestions is actually necessary, and none will guarantee that you will get into the US, but they may give you some peace of mind.