no, it was just a weed type plant that was growing (about 3.5 in tall) in the backyard.

but actually i have some pictures of the plant, and the mostly uncropped original photo. i shall post now...

also, I meant when I found it it was 3 1/2 in tall but until the aphids came it grew another inch and a half or so.

Two plants look like this (woolly-white stem with white leaf underside): Sweet Everlasting (Pseudognaphalium obtusifolium) and Pearly Everlasting (Anaphallis margaritacea), both in the aster family (Asteraceae). It is a hard choice without seeing the flowers, but I am leaning toward Sweet Everlasting (also known as Cudweed or Catsfoot) because the upper leaf surface has cobwebby hairs on the vein and tiny stalked glands on the blade; also the tips of the leaves are bluntly pointed, not sharply pointed. Check both species to see which seems a better fit to you.

i just grabbed a random plant that fit the size requirement and pull it out of the ground and repotted it into the terrarium. So weird is that a while later all the aphids disappeared and then the plant died.

Do you have a photo with a wider view of the plant, perhaps the uncropped original? If that could be posted here, I may be able to identify the plant, which could in turn help to identify the aphid.