Snakes are considered Mildly Venomous when any aspect of their bite due to modified saliva or toxin delivery system (such as fangs) which deliver toxins causes a reaction in their prey or would-be predators as long as they are not considered generally dangerous to humans . Although none of these species are considered "Dangerous to Humans". Most agree that they utilize their "toxins" to subdue prey items and is not generally used as a defense. Some merely have modified saliva and some have "fangs" like the Lyre Snake (a rear-fanged snake) that introduce toxins into prey. Some would argue whether or not these snakes should be even considered "mildly venomous". I base this description solely on the fact that bites from these snakes could potentially cause an adverse reaction in SOME humans. I have handled all of these species and do so with out hesitation. Keep in mind however that if you decide to do so that reaction to bites from these species depends on the person bitten; just like some can take several hundred bee stings and others can have a fatal reaction to just one.
Mexican Hognose Snake (H. n. kennerlyi)
Spotted night Snake (H. t. ochrorhyncha)
Texas Lyre Snake (T. b. vilkinsoni)