I planted what I thought was Romain lettuce in with some greens,but the leaves stayed small and now there are long bare stalks going up with yellow flowers on them. Is this Romain? The other, more numerous plants are collards and other greens.
I agree with Yvonne - some kind of cabbage-family plant. The confirmation would be if each flower has four petals - lettuce flowers will have many rays like a dandelion.