Rattlesnakes can only breed with other rattlesnakes (the family Viperidae). Rattlesnakes are too biologically different for it to be possible for them to breed with non-venomous snakes.

Interspecific hybridization has been invoked as a mechanism to explain the distribution of these toxins across rattlesnakes, with the implicit … We’re going to discuss what hybrid snakes are, and which species of snakes can interbreed. One of the snakes that are far more common is the Western rattlesnake Crotalus oreganus, specifically the Great Basin rattlesnake, a subspecies. The western diamondback's range extends into western Arkansas, much of Texas, eastern and south-central Oklahoma, southern and central Arizona, New Mexico, southernmost Nevada, southern California and …

Mojave rattlesnake neurotoxins cause rapid, respiratory constriction or paralysis, and then heart failure (in mice and kangaroo rats, their favored prey), but actually rarely kill humans.

Reality is that people just aren’t great at estimating size, especially at distance, from memory, or of an animal that causes anxiety or fear.

Another species they cross paths with is the Mojave rattlesnake, Crotalus scutulatus. ... Calif., where doctors recognized the symptoms as a bite from the especially toxic rattlesnake, the Mojave …

Mojave Green snake bites 6-year-old California boy, 42 vials of antivenom needed. Hemmorhagic toxins (the toxin of all other rattlesnakes) work slower, causing tissue destruction, then hemorrhaging if severe (but again, rarely fatal in humans).
Its range extends from southern Nevada and the southwestern part of Utah, along to Puebla and Veracruz in Mexico, and the western California Mojave Desert to west Texas.
The largest confirmed Mojave Rattlesnake ever recorded is 48″ long, or 4 feet long (Schuett, Feldner, Smith, Reiserer, Rattlesnakes of Arizona, pg 568).

There is no such thing as a bull snake rattlesnake hybrid. Rattlesnakes (Crotalus, Sistrurus) display extreme inter- and intraspecific variation in venom composition, centered particularly on the presence or absence of presynaptically neurotoxic phospholipases A 2 such as Mojave toxin (MTX). Sidewinder rattlesnakes live only in the furthest south part of the state, in the Mojave Desert.