As a DM and a Homebrew addict myself, I'll give advice and a little treat. 

First of all, if your gonna allow it and say yes, DM me. I already have a plant race you can fine tune and blah blah blah. If you want, which I recommend because more creative freedom, make your own plant race! Dryads, Nymphs, are an amazing start-up. 

A reason you might say no is because the plot and lore. In my experiences as a DM and player, it is extremely tough and possibly stressful to fully incorporate a entire race into a campaign is annoying if you have it all planned or have already started it. 

Something I do for certain races that only 1 or 2 people want to play is a curse. The characters are cursed by a conflict in the past. Dead family member, bandits they killed, even a simple broken twig could work.

Here's a race I made a while ago. Don't know if it's good or not. 

Homebrew Race: Woodfolk

In ancient forests, not yet discovered by society, nature gives birth to intelligent, plant-like humanoids. They create growing, blooming cities and kingdoms in these forests, but sometimes, they yearn for exploration and adventure. They will leave their homes and travel to lands of other races, where they establish relationships with them. These creatures are commonly called woodfolk. Their bodies are made of wood or vines, and in the spring, flowers will sprout out of them. Their native language is full of scraping, creaking sounds, and occasionally they will spend hours speaking and listening to nature. Most woodfolk do not use names. They do not think it necessary to remember such an unimportant thing. The only woodfolk who have names are the ones who are trying their best to fit in with other races.

 

Woodfolk Traits

Your woodfolk character possesses many talents and abilities that nature has gifted you.

   Ability Score Increase. Your Wisdom score increases by 2.

   Age. Woodfolk are long lasting and will continue to live until about 3,000 years have passed. If they die of old age, their body will turn dark and brittle, but if buried in good soil, a small sprout will eventually grow and create a new woodfolk. In this way, nature ensures that the woodfolk do not go extinct.

   Alignment. Woodfolk are very kind hearted, but they sometimes will do wild and unpredictable things with no explanation for their actions. They generally lean towards a chaotic good alignment.

   Size. Woodfolk can be under 5 feet to up to 7 feet tall, sometimes even higher. Your size is Medium.

   Speed. Your base walking speed is 30 feet.

   Darkvision. Your homelands were as black as a raven's feathers in the night, but your eyes are accustomed to it. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray.

   Nature Born. You have proficiency in the Nature skill.

   Understanding of Beasts. You can communicate simple ideas with Small or smaller animals that you touch, much like a forest gnome can.

   Forest Camouflage. You have advantage on checks made to hide in a forest environment.

   Regrowing Limbs. If you lose an arm or a leg, after one week, the limb is fully regrown. You cannot regrow your head. 

   Languages. You can speak, read, and write Common and the woodfolk language. As stated earlier in the description, woodfolk do not use names for many things. They did not even give their language a name. 

   Subrace. Two subraces of woodfolk are known to the world, the tree woodfolk and the vine woodfolk. Their names are simple ways to describe themselves, and woodfolk love simple things.

 

Tree Woodfolk

As a tree woodfolk, you are strong willed and tough, standing up for your beliefs without fear. You will not let anyone or anything force you to do something against your will. Your strong limbs are solid oak, which help you defend yourself against enemies.

   Ability Score Increase. Your Strength score increases by 1.

   Wooden Shield. You have the ability to grow a protective shield around yourself. During a short rest, you can spend the time transforming one of your arms into a shield. The shield gives you a +2 bonus to your AC, but while it lasts, you cannot use that arm to hold anything. The shield lasts until you finish a long rest.

   Natural Club. At 8th level, you gain the ability to use your arms as a club to bash and crush things. Treat both of your arms as greatclubs, but they deal 2d6 bludgeoning damage, and you can add your proficiency bonus to attack rolls.

 

Vine Woodfolk

As a vine woodfolk, you are a long-limbed, flexible being that quietly observes others. This is a more rare type of woodfolk that tries not to interfere with wars and politics of others. You are quick to react to any situation, though, and you do not give up on anything.

   Ability Score Increase. Your Dexterity score increases by 1.

   Reaching Vines. You can use a bonus action to extend your arms up to 15 feet, even while holding a weapon or object. At the end of your next turn, your arms revert back to their normal length.

   Thorny Vines. At 8th level, your arms have grown sharp thorns on them, and you gain the ability to attack with them. Make a melee weapon attack. If it hits, you deal 2d6 slashing damage. You can use this attack while you are using the reaching vines feature, too.