Blue Butterfly wings and blue mountain flowers are a multi-effect potion which gives you a nice amount of experience. They are two of the most common ingredients in the wild as well.
Go for a walk around the plains of whiterun and pick all the flowers, lavender, butterfly wings and tundra cotton you see. Butterfly wings and tundra cotton make potions of fortify barter. Lavender and blue butterfly wings/blue mountain flowers also make potions of fortify conjuration.
Then go for a walk in the snowy areas around Windhelm picking all the snowberries you see, then head south Kynesgrove-Riften way to the rocky areas and pick all the Dragon's Tongues you see. They'll make potions of resist fire. If you have any purple mountain flowers left over from your walk around Whiterun, they'll make potions of resist frost with snowberries. Leftover Tundra cotton and butterfly wings can be used to make fortify barter potions with Dragons Tongues.
And pick any thistles you see as well. They can be used to create resist frost potions.