There are several significant advantages of memristors, such as their nano scale, fast switching speed, power efficiency and compatibility with CMOS technology, as one of the alternatives in the next generation of semiconductor storage devices. D-flip-flops (DFFs) based on the traditional CMOS process have some shortcomings, including a large area, high power, and charge leakage when scaling down. However, memristors offer a new approach to the design of DFFs with improved performance. Two simplified edge-triggered DFFs are proposed to reduce the number of devices via the Memristor-Rationed Logic (MRL) method, which utilizes the characteristic of transmitting signals in the two-stage inversion structure. In addition, two new 4-bit Linear Feedback Shift Registers (LFSRs) are designed and verified using the proposed DFFs. Compared to the partially existing LFSRs, the designed LFSRs reduce the number of devices significantly, decrease the power consumption by 32.7% and 33.3% and shorten the delay time by 34.5% and 30.7% for the NOR and NAND gates, respectively. Finally, the proposed falling-edge-triggered DFF is used to implement the major blocks of the Built-In Self-Test(BIST) circuit, and the simulation results confirm their correctness and feasibility.