State trademarks do not require use in interstate commerce, federal marks do. If you used your state trademark in interstate commerce before the Texas company used its trademark, you might have superior rights to the Texas mark.
The above is general legal and business analysis. It is not "legal advice" but analysis, and different lawyers may analyse this matter differently, especially if there are additional facts not reflected in the question. I am not your attorney until retained by a written retainer agreement signed by both of us. I am only licensed in California. See also avvo.com terms and conditions item 9, incorporated as if it was reprinted here.
This sounds a lot like the (infamous) Zazu case. If the federal trademark issues, you will likely be restricted to use in the state of California, while the other party would have rights throughout the rest of the country.
If this is a real issue, you should speak with a trademark attorney in California and get a solid opinion.
This answer is not a substitute for professional legal advice. This answer does not create an attorney-client relationship, nor is it a solicitation to offer legal advice. If you ignore this warning and convey confidential information in a private message or comment, there is no duty to keep that information confidential or forego representation adverse to your interests. Seek the advice of a licensed attorney in the appropriate jurisdiction before taking any action that may affect your rights. If you believe you have a claim against someone, consult an attorney immediately, otherwise there is a risk that the time allotted to bring your claim may expire.
When examining new Federal trademark applications, the USPTO only checks for similar Federal trademark applications and registrations, not state trademarks. It is your job as the senior trademark owner to police the situation and oppose the Federal application before it is registered, or file a cancellation proceeding if the other mark has already registered.
Your state registration would precede the Federal registration and protect you in California. It could also be used to prevent your competition from coming into California. If you have made sales across state lines (or through the internet across state lines) then you could claim prior use and likely oppose the registration of the Texas company. You can sue based on likelihood of confusion in the marketplace if you had plans to go into Texas or if they try to come into California. All very fact specific.
This is not a legal opinion, and should not be relied upon as such.
Q: " ... do I have the right to sue?"
R: You have no cause to sue a person simply for filing a trademark registration application. You can, however, file an "opposition" proceeding with the Trademark Trial and Appeal Board ["TTAB"] to prevent that person's application from maturing into a registration. Your own trademark attorney will explain that process -- and will very likely reach out to the person beforehand to try to resolve the matter amicably.
You can file a trademark infringement lawsuit against the person, however, if the person is actually selling his or her similarly-branded clothes within the same geographic area where you sell your clothes. And no, just because you both sell via the internet does not mean that you both sell in the same geographic area. As my colleagues note, the person who USES a trademark first is its "senior user" -- even if someone else federally registers that mark first. In that case, the registration can be cancelled in a "cancellation" proceeding with the TTAB. But, again, just because you're the senior user does NOT mean that you have cause to sue the "junior user." The principal goal of trademark infringement law is prevent consumers from falsely believing that Company A's product is made by Company B. But that confusion can only occur if the consumers are exposed to BOTH companies' products. So if Company A only sells in the West Coast states and Company B sells only on the East Coast then there's [very likely] no overlap of consumers and so no likelihood of confusion.
Forget who registered what first. Lay out all the facts for your own trademark attorney and then figure out how to proceed. Good luck.
The above is general information ONLY and is not legal advice, does not form an attorney-client relationship, and should NOT be relied upon to take or refrain from taking any action. I am not your attorney. You should seek the advice of competent counsel before taking any action related to your inquiry.