1. Entry registration form. This can be used as evidence.
2. Attendance record. Although it is not stamped, it can be used in combination with other evidence.
3. Time card. Attendance cards generally do not need the company's seal. As long as your attendance card can be swiped on the attendance machine of the company, it can be proved that the card belongs to the company's attendance card.
4. Famous brand, work clothes and work photos. The evidence is not very effective, but it can also play a role when combined with other evidence.
5. The company document you signed.
6. Telephone recording. You can call the leader and ask him to say that you work in the company and record it.
7. Eyewitness testimony of colleagues. It will be better to find more colleagues to testify.
8. Relevant documents of the company.
The above evidence can be used together without a labor contract. The more evidence, the stronger the effectiveness of evidence after the formation of evidence chain. Among them, the evidence that can be printed on the other party's attendance machine, the company documents signed by you (preferably with company seal), attendance records and other evidence are still relatively powerful.
You don't need to give evidence during working hours, you just need to find evidence that can prove the existence of labor relations between you.
I hope it helps you.
Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.