Earth-Bound, otherwise known as Prairie ponies, are tough and strong creatures. They are without many of the fancy ornamentation of other ponies, but do well for themselves as they are.
Like a Rock: Once per long rest, when you are reduced to 0 hit points but not killed outright, you can drop to 1 hit point instead. In addition, whenever you roll a hit die to regain hit points, the minimum you regain is twice your Constitution modifier or 2, whichever is higher.
Like a Weed: You have advantage on saving throws against poison, and you have resistance against poison damage.
Show Jump: You have a high jump of 10 ft and a long jump of 20 ft, even from a standing start.
Ability Score Increase: Increase Constitution by 1.