I live in the state of Texas (Dallas area specifically). There is a field I drive by often near a residential neighborhood. Very open with not a person or house in sight (No signs or anything either). There seems to be a highway or something on the other side. Problem is, this field looks nice and I'd like to be in it. However, it's barbed wire fenced. BUT, there is an opening bigger than a person on the right side of the fence. There is no door to the field in sight. Would it be legal to enter the field through the opening? Will provide pictures if necessary.
The Dallas County Tax Office has information on property ownership so that taxes may be collected. A casual inspection of their site did not indicate any ability to display a map and use it to find the name of the owner of the property. They may offer this capability to the public in their office(s).
Ownership information may also be available at the Dallas County Clerk's office. A casual inspection of that site suggests online access might require a paid subscription, but if you visit the office in person, the information is likely to be available free or at nominal cost.
Once you determine the ownership, you might discover it is public land and you can contact the relevant agency to confirm it is open to the public. If it turns out to be private, you may be able to contact the owner to request permission to enter.
I am not familiar with the trespass laws in Texas; I don't know if permission to enter is required in the situation you described.
Entering onto someone's land without lawful excuse is trespass
Permission is lawful excuse. You don't have express permission. You have implied permission to enter in some circumstances, for example, to approach someone's front door or to reasonably recover your property.
You would also have lawful excuse if you were a police, fire or ambulance officer discharging their duties or if you were in physical danger if you didn't enter - running from an assailant across someone else's property is not trespass. Among others.
Whether the field is fenced or not or if that fence has an opening or gate does not give you permission although it can remove some implied permissions, not least that you do not have implied permission to enter over the fence.
If its not your field, stay out of it.