My roommates and I have been wanting to play dnd for a while but it’s not easy finding a group so I decided to try my hand at DMing with a one shot I’m creating. The players will be level 8 but I’m not sure what kind of equipment and items they should start off with. Any pointers and advice (with equipment and DMing) would be greatly appreciated. 

Also for the one shot I was thinking of having a corpse flower mind controlling (it stumbled upon a mind control magic scroll) a kid to lure people into this rundown mansion where other monsters await them. They would need to figure out what happened to the missing people and put a stop to the matter. If it goes well and they like it I was thinking of switching it to a full on campaign where an evil wizard, with the help of another nations government, are doing experiments all over the continent like the one they’re stopping in the one shot. 

What equipment and treasure characters have is highly dependent on DM based on amount of coins, gems and magic items they come across. 

As DM it's not too uncommon in my campaigns for a level 8 character to have one of the pricier armor of it's kind, silver weapon, one or two permanent magic item and two yo three consumable magic items like a potion or scroll.

If you're trying your hand for the first time at DMing, and if this is the first time most of you are playing DND, I might gently recommend against doing a level 8 homebrew one-shot. There are plenty of resources for very fun one-shots that are lower level and easier to manage. 

That being said if you've played before and you're comfortable with it, then check out Xanathar's Guide to Everything. In that book, I forget where exactly, you can see a breakdown of "expected" treasure and magic items per character level and per tier of play. That's a good resource to a least get a baseline before deciding if you wanna do more or less magic than average. 

Yeah, I also caution against an 8th level one-shot for your first game. There are a lot of rules to this game, and a lot of skills and abilities the players will need to understand in order to play the game properly. If anyone wants to play a spellcaster, they'll need to select and understand the use of at least 10 spells across 4 different levels of spell slots. I think I would drop it down to a 4th level one-shot... levels 1-2 can be really challenging for new players, even though they really should be the simplest jumping on point for the game... mostly it's just because it's really, really easy to lose all your HP at those levels. At level 3 every player will have the opportunity to pick out their subclass, and taking it one level higher to level 4 is fairly simple (since it's an ASI level), so any player willing to take the time to read through and select a feat can use one, while everyone else can just boost their primary stat.

Anyway, I don't think you'll really need any magic items or special equipment for a one shot. If you just want to make the game a bit easier for new players, just give everyone a +1 weapon or armor, or a +1 spellcasting focus.

Being a GM can be a tough job. To make things easier, I would recommend starting at a lower level. Even if you have played higher, being a GM is a whole different thing. If your players also lack experience then starting at a lower level will help them too. Level 2 would be my suggestion. Then when they level up they feel empowered.

Regarding items and magic, since they are starting at low level, they don't need any or you can throw them a couple potions or scrolls.

If you insist on starting higher, then give them one of the basic start kits - dungeoneers or explorers pack and whatever non-magical armor and weapons they want. One rare or two uncommon items.