No 2 is a chick weed - possibly Stellaria media.

The seeds in the first picture don't look like tree seedlings to me. Did you have something other than sunflowers in the feeder ever? They appear to have serrated true leaves like something in the thistle tribe. Or can you remember what flowers were growing there last year?

The third plant is an Umbelifer but there are hundreds and Texas is way out of my knowledge area.

#9 may be the same as plant #1, wild carrot or Queen Anne's lace.
hortster

#7 look like safflower seedlings. Safflower seeds are often mixed with sunflower seeds for wild birds, sometimes accidentally.