Urrrg...

[Jenna!]

My friend keeps making me solve riddles for her, and they are really hard. Can you help me... Again?

Colours vary, sail I will,
Many sunny moments fill.
Allergies set to the ground,
Plenty time spent nice and round.

[Articfox]

Sounds like a flower to me or something, oh and the flashing eyes smiley is just creepy and scary.

[iconoplast]

The best I can come up with is pollen, but I don't know if that fits the "Colours vary" requirement.

[halfbakedbliss]

Its a flower, it really matches all the lines if you think about it.

[.ccy]

some round flower

[DiscordantNote]

A flower, maybe a dandelion since they change color (sort of), are round-shaped, cause allergies, and are a very bright yellow when they're not in puff-ball mode.

EDIT: Their seeds also float on the wind, hence the 'sailing'.

[ahoteinrun]

I agree with Discordant Note.
I think it's a dandelion (though I figured it out before reading Discordants answer... *sulks*)

[Jim]

I'd say pollen too, but it doesnt seem quite right for some reason.

[Crystal Cloud]

i think its a dandelion also.

[Amethyst]

I'm going to go ahead and say dandelion, because it makes sense.

[Jenna!]

Thanks you guys!!!

*Sigh* My friend decided 'Since I am SOOOO good with riddles' that she is going to give me one every week!!!

And just ot be creepy...

[Raven Poet]

Perhaps flower petals? That's a hard one...

[Fiddelysquat]

A buffalo!

[halfbakedbliss]

Actually, I change my theory, I agree with Fidds now