I have The Culling of the Cows and Uriel's Chasm steam keys, but can't create a giveaway

Both were for free, so guess again why you cannot create giveaway for them!

Give them to someone who doesn't have them, games were given free so they've been removed.
Uriel Chasm,The Culling of the Cows
The links above are for the giveaways.

You can either hold on to them until a later time, or simply drop them on the forums. Or hand them off to family members or something? I'm sorry for you, but those were apparently either very discounted or free recently, and as such you cannot get CV for them.