Plant identification help!

[DuckWhisperer06]

I need some help identifying these plants. Our neighbor is growing milo and sweet corn on the property around ours. I walked out earlier to see how the corn was doing and found some weird plants. Any idea what they are?

Plant A: long pointed leaves.
Reddish-pink stem.

Plant B: Shorter, rounded leaves. Pink-red ‘striped’ stem.

Plant C: Pinkish-Red towards the root. Leaves feel kind of like plastic.

 

[Wyorp Rock]

Looks like Pig Weed (amaranth) to me.

 

[woodmort]

Without knowing where you live, I'd guess it's some sort of pigweed.

 

[woodmort]

The pigweed I'm familiar with is what is found in the NE and Midwest but there are a of varieties that fall under the name.